Abstract
Background
Racial disparities in lung cancer have existed in the United States (US) for many years. No studies have been conducted to elucidate the long-term trends of racial disparities in all-cause and cause-specific deaths in lung cancer patients. Our study aimed to explore trends and potential contributing factors of racial disparities.
Methods
From the Surveillance, Epidemiology, and End Results (SEER) Program, we obtained the data of lung cancer patients diagnosed between 2000 and 2019, with follow-up until Dec 31, 2020. The cumulative mortality for Black, White, Asian or Pacific Islander (API), and American Indian or Alaska Native (AIAN) was calculated by diagnostic period and cause of death. By using Cox regression models, we determined the relative [hazard ratio (HR)] racial disparities and contributing factors.
Results
The incidence and mortality rates during 2000–2019 for lung cancer decreased in all racial groups in men and women, especially for Black men. Despite a downward trend in the cumulative risk of death in racial groups, Black and API patients consistently had the highest and lowest mortality rates from 2000 to 2019, with adjusted HR of 1.14 and 0.83, respectively. The Black-White disparities in all-cause mortality narrowed over time, with adjusted HR of 1.18 [95% confidence interval (CI): 1.15–1.20] during 2000–2004 and 1.14 (95% CI: 1.11–1.16) during 2015–2019. Surgery and liver metastasis had the largest effect on Black-White disparities and API-White disparities, respectively.
Conclusions
Our findings reveal persistent racial disparities among lung cancer patients, providing a theoretical basis for interventions to eliminate health disparities.
Keywords: Racial disparities, lung cancer, mortality
Highlight box.
Key findings
• The incidence and mortality rates of lung cancer declined across all racial groups, especially for Black men. But Black and Asian or Pacific Islander (API) patients consistently had the highest and lowest mortality rates respectively.
• The Black-White disparities in all-cause mortality narrowed over time.
• Surgery and liver metastasis had the largest effect on Black-White disparities and API-White disparities, respectively.
What is known and what is new?
• Racial disparities in lung cancer have existed in the United States for many years.
• This study provides a comprehensive analysis of long-term trends in racial disparities in all-cause and cause-specific mortality among patients with lung cancer.
What is the implication, and what should change now?
• Our findings reveal persistent racial disparities among lung cancer patients, providing a theoretical basis for interventions to eliminate health disparities.
• To further investigate the underlying socioeconomic determinants of racial disparities, access to individual-level data on socioeconomic status and lifestyle factors is essential.
Introduction
Lung cancer is one of the most common and deadly malignancies. In 2023, an estimated 238,340 people are initially diagnosed with lung cancer and 127,070 lung cancer-related deaths occur in the USA, accounting for 12.2% of all cancer cases and 20.8% of all cancer deaths (1). In 2019, lung cancer patients caused a net economic burden of $1.5 billion (2). With the increasing age of the population, the incidence and mortality of lung cancer will further rise, leading to an increasing burden on the health care system and the economy. With the clinical application of targeted therapy and immunotherapy, the poor 5-year overall survival rate of lung cancer has improved to a certain extent; however, this improvement is not uniform across ethnic groups (1,3). Increasing evidence shows that high adverse effects and poor life quality in racial minorities with lung cancer affect the outcome of the survivors (4). Clarifying trends and potential contributors to racial disparities in lung cancer incidence and mortality may provide additional rationale for improving outcomes and promoting health equity across all races.
The disparities in lung cancer incidence and outcomes by race/ethnicity could be affected by many factors, including physical environmental, socioeconomic, socio-environmental, behavioral and biological factors (5). Given similar smoking history, African Americans/Blacks had a significantly higher relative risk of lung cancer compared with non-Hispanic Whites (5). Another investigation shows that Black residents in Chicago have a higher risk of lung cancer partly attributed to higher neighborhood violence (6). Moreover, Black individuals are associated with advanced-stage disease compared with White individuals, leading to different overall survival (7). Asian patients experience greater difficulty accessing timely care, necessary medical services, and prescribed medications compared to White patients (8). When analyzing racial disparities in cancer patients, competing risks of non-cancer-related death should not be considered. For example, middle-aged Black adults have a higher risk of chronic disease than the White counterparts, which may affect the clinical outcome of cancer patients (9). Thus, clarifying trends and patterns in lung cancer patients in different races is very vital for promoting health equity for all.
In our study, we comprehensively investigated trends in the causes of lung cancer death in the USA over a 20-year period based on the most recent data available from the Surveillance, Epidemiology, and End Results (SEER) database. Our findings may provide additional evidence of effective interventions for racial health disparities to bridge the racial disparities in the prevention, diagnosis, treatment, and follow-up of lung cancer in USA. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-333/rc).
Methods
Data sources
From SEER database (https://seer.cancer.gov/), we obtained research data from 17 registries, including Greater Georgia, San Francisco-Oakland SMSA, New Jerey, Connecticut, Louisiana, Hawaii, Kentucky, Iowa, California excluding SF/SJM/LA, New Mexico, Rural Georgia, Seattle (Puget Sound), Alaska Natives, Utah, Los Angeles, San Jose-Monterey, Atlanta (Metropolitan), ranking for about 26.5% of the US population in the 2020 census. The demographic information of patients from the health service was retrieved by the staff of cancer registries regularly. Those cases diagnosed with lung cancer between 2000 and 2019 were included in our study and processed with SEER*Stat software (version 8.4.2). The variables of lung cancer cases, including age, tumor grade, radiotherapy, etc., are shown in Table S1. Based on Census Bureau of the USA, race of population could be separated into four categories [White, Black, Asian/Pacific Islander (API), American Indian/Alaska Native (AIAN)]. We classified the tumor grade based on “Grade Recode (thru 2017)” and “Grade Pathological (2018+)”. Stage, T stage, N stage, and M stage were classified using “Derived AJCC Stage/T/N/M Group, 6th ed (2004–2015)”, “Derived SEER Combined Stage/T/N/M Group (2016–2017)” and “Derived EOD 2018 Stage/T/N/M Group (2018+)”. Regional nodes examined were classified into three groups, including “n=0”, “n=1–15”, and “n≥16” (10). Tumor size was classified into two groups, including “≤7 cm”, “>7 cm” (11). Income is defined as median household income. Surgery status, radiotherapy status and chemotherapy were determined based on the SEER coding. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.
The clinical outcome of lung cancer cases
Lung cancer cases were followed up from the date of diagnosis until the patient’s death or censored on December 31, 2020. The revisions of International Classification of Diseases editions (ICD), tenth (ICD-10) were used to code the causes of lung cancer case deaths. The causes of death were clustered into two main groups, including lung cancer specific death and causes other than lung cancer. Causes other than lung cancer were subdivided into chronic obstructive pulmonary disease (COPD), diseases of heart, miscellaneous cancers, other specific causes and unknown causes. Table S2 showed these mutually exclusive and comprehensive causes of death.
Statistical analysis
Missing data were dealt with using the linear interpolation method with R package “zoo”. Fine and gray model was used to evaluate the cumulative incidence of 5-year overall death and specific cause death. The competing risks of death included race/ethnicity, tumor grade, stage, and diagnostic period. As most Americans are White, White population was set as the reference group for the comparisons between pairwise races. Diagnostic year were categorized into four periods (2000–2004, 2005–2009, 2010–2014, and 2015–2019). Absolute and relative racial disparities were calculated, which can depict more comprehensive racial disparities over time. To quantify the absolute racial disparities, we calculate the absolute rate of the 5-year cumulative incidence of death between the period 2010–2014 (the most recent period for such data that are available) and the period 2000–2004. After adjusting for age as a categorical variable (<60, 60–69, 70–79, 80+ years), we developed the cause-specific hazard regression model. The multiplicative interaction term between race and diagnostic period was added to the regression models, which could explore the changing trends of differences in racial disparities over time. The product term treated the diagnostic period as a continuous variable. The diagnostic period in the main effect was considered a continuous variable, which is the same as that in the interaction term. Univariable and multivariable analyses were conducted to identify clinical risk factors affecting racial disparities of lung cancer-related death, which were referred to as candidate covariates in mediation analysis. To evaluate the contribution of each covariable to racial disparities in lung cancer-related death, we then performed a mediation analysis (12). With these calculations, we could determine the direct effects, indirect effects, total effects and mediated proportion for candidate covariates in racial disparities of lung cancer-related death. We also performed several subgroup analyses based on each covariate, which could further clarify the correlation of baseline characteristic differences with lung cancer-related death. R software (version 4.2.2) was used to conduct all statistical analyses. Statistically significant difference was considered when the bilateral P value was less than 0.05.
Results
After a rigorous selection process (Figure S1), we included a total of 443,132 lung cancer cases in our study, including 361,526 White race (81.6%), 47,841 Black race (10.8%), 31,201 API race (7.0%), and 2,564 AIAN race (0.6%) (Table S1). A total of 372595 (84%) lung cancer cases of the total cohort died during follow-up, including 307,157 (69%) from lung cancer and 65,438 (15%) from causes other than lung cancer. The mean age at diagnosis was 67.19 years, and the age of diagnosis was the youngest among Black patients. Only 17.7% (79,029) of cases were diagnosed with stage I/II. AIAN patients had the largest proportion of lymphatic metastasis. Among all race groups, API had the highest proportion of distant disease while White had the lowest. A total of 26% of White patients received surgery, the highest rate among any racial group.
The trends in incidence rates during 2000–2019 for lung cancer by sex and race are shown in Figure 1A. During this period, an overall decreased incidence rate was seen in all racial groups, with White men contributing the most, except for a fluctuating increase in incidence rates for AIAN in both men and women. In API females, incidence rates for lung cancer steadily increased during 2000–2019. As shown in Figure 1B, the mortality rates during 2000–2019 for lung cancer decreased in all racial groups in both men and women especially among Black men except for API women whose rates did not decrease. It is worth noting that the mortality rates for AIAN in both men and women showed an upside-down fluctuation in the first decade, but then steadily declined (Figure 1B).
Figure 1.
Trends in annual age-standardized rates for the incidence and death of lung cancer by race and sex in the USA. Trends in age-standardized incidence (A) and mortality (B) rates among males and females. Rates are per 100,000 population and age-adjusted to the 2020 US standard population. AIAN, American Indian/Alaska Native; API, Asian or Pacific Islander.
Figure 2 and Table S3 showed the cumulative incidence of all-cause and cause-specific death during 2000–2019. The 5-year cumulative mortality from lung cancer was 69.5%, followed by diseases of the heart at 2.7% and COPD at 1.8% (Figure 3A,3B and Table S3). With the extension of follow-up, the 10-year cumulative incidence of death from lung cancer was 72.9%, which is not far from the 5-year cumulative incidence of death (Figure S2 and Table S3). Among all racial groups, Black patients had the highest 5-year cumulative incidence of overall death (84.9%), followed by AIAN patients (84.5%), White patients (81.8%), and API patients (77.4%). As expected, decreasing trends were seen in the cumulative risk of death in 2000–2019 in all racial groups (Table 1). At each time period, the 5-year cumulative incidence of all-cause death was highest among Black patients, followed by AIAN patients (Table 1). We also found that API patients had the largest reduction in 5-year cumulative all-cause mortality and AIAN patients had the largest reduction in 5-year cumulative lung cancer-specific mortality.
Figure 2.
Cumulative incidence of all-cause and cause-specific death in lung cancer patients. COPD, chronic obstructive pulmonary disease.
Figure 3.
The 5-year cumulative incidence of all-cause (A) and cause-specific death (B) in lung cancer patients by race and diagnostic period. AIAN, American Indian/Alaska Native; API, Asian or Pacific Islander; COPD, chronic obstructive pulmonary disease.
Table 1. 5-year cumulative incidence of all-cause and cause-specific death in lung cancer patients by race and diagnostic period, 2000–2019.
| Group | 5-year cumulative incidence of death (95% CI), % | |||||||
|---|---|---|---|---|---|---|---|---|
| Overall | Lung cancer | Causes other than lung cancer | COPD | Diseases of Heart | Miscellaneous cancers | Other specific causes | Unknown causes | |
| All patients | ||||||||
| 2000–2019 | 81.8 (81.7–81.9) | 69.5 (69.3–69.6) | 12.3 (12.2–12.4) | 1.6 (1.6–1.7) | 2.7 (2.6–2.7) | 2.1 (2.0–2.1) | 4.5 (4.4–4.5) | 1.5 (1.5–1.5) |
| 2000–2004 | 86.9 (86.6–87.1) | 75.6 (75.3–75.8) | 11.3 (11.1–11.5) | 1.4 (1.3–1.4) | 2.9 (2.8–3.0) | 2.2 (2.2–2.3) | 3.8 (3.7–3.9) | 1.0 (1.0–1.1) |
| 2005–2009 | 84.6 (84.3–84.8) | 72.5 (72.3–72.8) | 12.0 (11.8–12.2) | 1.6 (1.5–1.6) | 2.6 (2.5–2.7) | 2.1 (2.0–2.2) | 4.5 (4.4–4.6) | 1.3 (1.2–1.3) |
| 2010–2014 | 81.4 (81.2–81.6) | 69.2 (68.9–69.5) | 12.2 (12.0–12.4) | 1.7 (1.7–1.8) | 2.5 (2.4–2.6) | 2.0 (1.9–2.0) | 4.5 (4.4–4.6) | 1.5 (1.4–1.6) |
| AC (%) | −5.5 | −6.4 | 0.9 | 0.3 | −0.4 | −0.2 | 0.7 | 0.5 |
| White | ||||||||
| 2000–2019 | 81.8 (81.6–81.9) | 69.5 (69.3–69.6) | 12.3 (12.2–12.4) | 1.8 (1.8–1.9) | 2.7 (2.7–2.8) | 2.0 (2.0–2.1) | 4.2 (4.1–4.3) | 1.5 (1.5–1.6) |
| 2000–2004 | 86.6 (86.4–86.8) | 75.5 (75.2–75.8) | 11.1 (10.9–11.3) | 1.5 (1.4–1.6) | 2.9 (2.8–3.0) | 2.2 (2.1–2.3) | 3.5 (3.4–3.7) | 1.0 (1.0–1.1) |
| 2005–2009 | 84.4 (84.1–84.6) | 72.5 (72.2–72.8) | 11.9 (11.7–12.1) | 1.7 (1.6–1.8) | 2.6 (2.5–2.7) | 2.1 (2.0–2.2) | 4.2 (4.0–4.3) | 1.3 (1.2–1.4) |
| 2010–2014 | 81.3 (81.1–81.6) | 69.1 (68.8–69.4) | 12.2 (12.0–12.5) | 1.9 (1.8–2.0) | 2.6 (2.5–2.7) | 1.9 (1.8–2.0) | 4.3 (4.1–4.4) | 1.6 (1.5–1.6) |
| AC (%) | −5.3 | −6.4 | 1.1 | 0.4 | −0.3 | −0.3 | 0.8 | 0.6 |
| Black | ||||||||
| 2000–2019 | 84.9 (84.6–85.3) | 71.6 (71.2–72.1) | 13.3 (13.0–13.6) | 1.0 (0.9–1.1) | 2.8 (2.7–3.0) | 2.5 (2.3–2.6) | 5.5 (5.3–5.7) | 1.5 (1.4–1.6) |
| 2000–2004 | 90.0 (89.4–90.6) | 78.1 (77.3–78.9) | 11.9 (11.3–12.6) | 0.7 (0.6–0.9) | 3.0 (2.7–3.3) | 2.7 (2.5–3.1) | 4.4 (4.0–4.8) | 1.1 (0.9–1.3) |
| 2005–2009 | 87.9 (87.3–88.5) | 74.7 (73.9–75.5) | 13.2 (12.6–13.8) | 1.0 (0.8–1.2) | 2.5 (2.2–2.8) | 2.6 (2.3–2.9) | 5.9 (5.5–6.3) | 1.3 (1.1–1.5) |
| 2010–2014 | 84.5 (83.9–85.1) | 71.6 (70.8–72.4) | 12.9 (12.3–13.5) | 1.1 (1.0–1.3) | 2.7 (2.4–3.0) | 2.3 (2.0–2.5) | 5.4 (5.0–5.9) | 1.4 (1.2–1.6) |
| AC (%) | −5.5 | −6.5 | 1 | 0.4 | −0.3 | −0.4 | 1 | 0.3 |
| API | ||||||||
| 2000–2019 | 77.4 (76.9–77.9) | 66.0 (65.5–66.6) | 11.4 (11.0–11.4) | 0.6 (0.6–0.7) | 2.0 (1.9–2.2) | 1.9 (1.7–2.0) | 5.9 (5.6–6.2) | 1.0 (0.9–1.1) |
| 2000–2004 | 84.7 (83.7–85.7) | 71.8 (70.6–73.0) | 12.9 (12.0–13.8) | 0.6 (0.4–0.8) | 2.7 (2.3–3.2) | 2.5 (2.1–2.9) | 6.3 (5.7–7.0) | 0.8 (0.6–1.0) |
| 2005–2009 | 81.4 (80.5–82.4) | 69.5 (68.4–70.7) | 11.9 (11.1–12.7) | 0.8 (0.6–1.1) | 2.0 (1.7–2.4) | 1.8 (1.6–2.2) | 6.3 (5.7–6.9) | 0.9 (0.7–1.2) |
| 2010–2014 | 77.5 (76.6–78.4) | 66.7 (65.7–67.8) | 10.7 (10.1–11.4) | 0.6 (0.5–0.8) | 1.8 (1.5–2.1) | 1.6 (1.4–1.9) | 5.7 (5.3–6.3) | 0.9 (0.7–1.2) |
| AC (%) | −7.2 | −5.1 | −2.2 | 0 | −0.9 | −0.9 | −0.6 | 0.1 |
| AIAN | ||||||||
| 2000–2019 | 84.5 (83.0–86.0) | 71.6 (69.8–73.4) | 12.9 (11.6–14.3) | 1.1 (0.8–1.6) | 1.9 (1.4–2.5) | 2.4 (1.9–3.1) | 5.9 (5.0–6.9) | 1.6 (1.2–2.2) |
| 2000–2004 | 88.9 (86.2–91.7) | 78.2 (74.8–81.9) | 10.7 (8.3–13.7) | 1.0 (0.4–2.3) | 2.3 (1.3–4.1) | 2.5 (1.5–4.3) | 4.1 (2.7–6.2) | 0.8 (0.3–2.1) |
| 2005–2009 | 87.9 (85.4–90.6) | 77.2 (73.9–80.7) | 10.7 (8.5–13.5) | 1.7 (0.9–3.1) | 2.2 (1.3–3.8) | 2.0 (1.2–3.6) | 3.2 (2.1–5.0) | 1.5 (0.8–2.9) |
| 2010–2014 | 83.0 (80.1–85.9) | 70.4 (66.9–74.0) | 12.6 (10.3–15.4) | 1.2 (0.6–2.5) | 1.7 (1.0–3.1) | 3.1 (2.0–4.8) | 3.7 (2.5–5.5) | 2.8 (1.8–4.4) |
| AC (%) | −5.9 | −7.8 | 1.9 | 0.2 | −0.6 | 0.6 | −0.4 | 2 |
The absolute changes for the 5-year cumulative incidence of death were calculated between the period 2000–2004 and the period 2010–2014. AC, absolute change; AIAN, American Indian/Alaska Native; API, Asian or Pacific Islander; CI, confidence interval; COPD, chronic obstructive pulmonary disease.
Table 2 and Table S4 showed relative and absolute disparities for all-cause and cause-specific death in different races of lung cancer patients during 2000–2019. The absolute difference in the cumulative incidence of all-cause death between API patients and White patients over the 5-year period from 2000–2004 was −1.9%, and decreased to −3.8% during 2010–2014 (Table 2). Although the absolute disparity in all-cause mortality and lung cancer-specific mortality between Black and White patients did not change much from 2000–2004 to 2010–2014, the relative disparities declined steadily (Table 2). A widening relative disparity was found in both lung cancer mortality and causes other than lung cancer mortality between API and White patients. The adjusted HR of AIAN-White disparities for causes other than lung cancer mortality increased from 1.01 in 2000–2004 to 1.47 in 2015–2019, indicating a widening disparity.
Table 2. Adjusted hazard ratios and absolute disparities for all-cause and cause-specific death in different race of lung cancer patients in the USA, 2000–2019.
| Group | Overall | Lung cancer | Causes other than lung cancer | COPD | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| HR (95% CI) | AD (%) | HR (95% CI) | AD (%) | HR (95% CI) | AD (%) | HR (95% CI) | AD (%) | ||||
| Black vs. White | |||||||||||
| 2000−2019 | 1.14 (1.13−1.15) | 3.1 | 1.06 (1.05−1.08) | 2.1 | 1.17 (1.14−1.20) | 1.0 | 0.65 (0.60−0.70) | 1.0 | |||
| 2000−2004 | 1.18 (1.15−1.20) | 3.4 | 1.08 (1.05−1.10) | 2.6 | 1.21 (1.15−1.27) | 0.8 | 0.66 (0.56−0.78) | 0.8 | |||
| 2005−2009 | 1.16 (1.14−1.19) | 3.5 | 1.07 (1.05−1.09) | 2.2 | 1.22 (1.17−1.28) | 1.3 | 0.73 (0.63−0.84) | 1.3 | |||
| 2010−2014 | 1.13 (1.11−1.16) | 3.2 | 1.06 (1.04−1.09) | 2.5 | 1.16 (1.11−1.22) | 0.7 | 0.70 (0.60−0.81) | 0.7 | |||
| 2015−2019 | 1.14 (1.11−1.16) | 1.09 (1.07−1.12) | 1.20 (1.14−1.27) | 0.67 (0.56−0.81) | |||||||
| P for trend | 0.003 | 3.0×10−4 | 0.87 | 0.50 | |||||||
| API vs. White | |||||||||||
| 2000–2019 | 0.83 (0.82–0.84) | −4.4 | 0.78 (0.77–0.79) | 0.0 | 0.75 (0.72–0.77) | −0.4 | 0.28 (0.25–0.32) | 0.1 | |||
| 2000–2004 | 0.89 (0.87–0.92) | −1.9 | 0.83 (0.81–0.86) | 0.1 | 0.90 (0.85–0.97) | −1.2 | 0.32 (0.25–0.42) | 0.3 | |||
| 2005–2009 | 0.86 (0.83–0.88) | −3.0. | 0.81 (0.78–0.83) | 2.5 | 0.81 (0.77–0.87) | −2.5 | 0.35 (0.28–0.43) | 0.7 | |||
| 2010–2014 | 0.85 (0.83–0.87) | −3.8 | 0.82 (0.80–0.84) | −1.2 | 0.77 (0.72–0.82) | −0.3 | 0.31 (0.24–0.39) | 0.1 | |||
| 2015–2019 | 0.81 (0.79–0.84) | 0.81 (0.79–0.84) | 0.67 (0.63–0.72) | 0.21 (0.15–0.29) | |||||||
| P for trend | 2.21×10−7 | 1.29×10−8 | 0.01 | 0.62 | |||||||
| AIAN vs. White | |||||||||||
| 2000–2019 | 1.09 (1.05–1.14) | −0.4 | 1.08 (1.03–1.13) | −3.5 | 1.16 (1.04–1.28) | −0.9 | 0.75 (0.55–1.02) | −1.2 | |||
| 2000–2004 | 1.07 (0.98–1.16) | −1.1 | 1.04 (0.95–1.15) | −3.7 | 1.01 (0.81–1.26) | 1.8 | 0.74 (0.41–1.33) | −0.9 | |||
| 2005–2009 | 1.11 (1.03–1.21) | 0.0 | 1.07 (0.98–1.18) | −3.0 | 1.18 (0.95–1.46) | 0.0 | 1.07 (0.62–1.84) | −0.9 | |||
| 2010–2014 | 1.05 (0.97–1.14) | −1.5 | 1.11 (1.03–1.21) | −2.4 | 1.16 (0.95–1.41) | −1.5 | 0.68 (0.36–1.32) | −1.3 | |||
| 2015–2019 | 1.22 (1.12–1.32) | 1.25 (1.14–1.37) | 1.47 (1.22–1.76) | 0.63 (0.28–1.40) | |||||||
| P for trend | 0.23 | 0.42 | 0.02 | 0.75 | |||||||
The absolute disparities for the 5-year cumulative incidence of death were calculated using White patients as the reference category. All cause-specific Cox regression models were adjusted for age as a categorical variable (<60, 60–69, 70–79, 80+ years). P for trend values were calculated by the interaction term between race/ethnicity and diagnostic period in regression model. AD, absolute disparity; AIAN, American Indian/Alaska Native; API, Asian or Pacific Islander; CI, confidence interval; COPD, chronic obstructive pulmonary disease; HR, hazard ratio.
Univariable and multivariable cox analysis showed that age, sex, household income, primary site, tumor grade, tumor size, clinical stage, T stage, N stage, M stage, bone metastasis status, brain metastasis status, liver metastasis status, lung metastasis status, surgery status, regional nodes examined, radiotherapy, and chemotherapy significantly correlated with the risk of death from all causes (Table S5). Thus, we then quantified the relative contributions of these factors to racial disparities between White patients and Black patients as well as API patients, for all-cause mortality and cause-specific mortality. As shown in Table 3 and Table S6, surgery exerted the largest effect on Black-White disparities in death from all causes, causes from lung cancer and causes other than lung cancer, with 112.8%, 100% and 134.4% of disparities. Liver metastasis had the largest effect on API-White disparities in death from all causes, causes from lung cancer and causes other than lung cancer, followed by bone metastasis, brain metastasis and lung metastasis (Table 4 and Table S6). Table 5 lists the adjusted HRs for death in patients with lung cancer according to the clinicopathological parameters. The adjusted HRs for Black-White disparities were higher in patients with well/moderately differentiated tumor than poorly/undifferentiated tumor. Compared with patients with lymphatic metastasis or distant metastasis, the adjusted HRs for Black-White disparities were higher in patients without lymphatic metastasis or distant metastasis. By radiotherapy and chemotherapy status, the relative Black-White disparities were still found in different therapy categories. We also found that the adjusted HRs for API-White disparities were higher in lung cancer patients without distant metastasis compared with patients with bone metastasis, brain metastasis, or liver metastasis.
Table 3. Causal mediation analysis for clinicopathological parameter with Black-White disparities in all-cause and lung cancer-specific death, 2000–2019.
| Variables | Overall | Lung cancer | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ACME | PACME | ADE | TE | Proportion | ACME | PACME | ADE | TE | Proportion | ||
| Income | 0.0058 | <0.001 | 0.008 | 0.014 | 0.408 | 0.0066 | <0.001 | 0.011 | 0.017 | 0.383 | |
| Age | −0.0108 | <0.001 | 0.025 | 0.014 | −0.760 | −0.0103 | <0.001 | 0.027 | 0.017 | −0.604 | |
| Sex | 0.0023 | <0.001 | 0.012 | 0.014 | 0.165 | 0.0028 | <0.001 | 0.014 | 0.017 | 0.165 | |
| Primary site | −0.0014 | <0.001 | 0.016 | 0.014 | −0.102 | −0.0020 | <0.001 | 0.019 | 0.017 | −0.117 | |
| Grade | 0.0031 | <0.001 | 0.011 | 0.014 | 0.222 | 0.0028 | <0.001 | 0.014 | 0.017 | 0.163 | |
| Stage | 0.0048 | <0.001 | 0.009 | 0.014 | 0.342 | 0.0043 | <0.001 | 0.013 | 0.017 | 0.254 | |
| T | 0.0028 | <0.001 | 0.011 | 0.014 | 0.198 | 0.0027 | <0.001 | 0.014 | 0.017 | 0.159 | |
| N | 0.0006 | 0.04 | 0.014 | 0.014 | 0.041 | −0.0001 | 0.90 | 0.017 | 0.017 | −0.005 | |
| M | −0.0004 | 0.004 | 0.015 | 0.014 | −0.032 | −0.0007 | 0.002 | 0.018 | 0.017 | −0.041 | |
| Surgery | 0.0160 | <0.001 | −0.002 | 0.014 | 1.128 | 0.0171 | <0.001 | 0.000 | 0.017 | 1.000 | |
| Radiotherapy | 0.0033 | <0.001 | 0.011 | 0.014 | 0.230 | 0.0041 | <0.001 | 0.013 | 0.017 | 0.237 | |
| Chemotherapy | 0.0002 | 0.24 | 0.014 | 0.014 | 0.017 | −0.0004 | 0.27 | 0.017 | 0.017 | −0.020 | |
| Bone metastasis | −0.0055 | <0.001 | 0.020 | 0.014 | −0.389 | −0.0055 | <0.001 | 0.023 | 0.017 | −0.319 | |
| Brain metastasis | −0.0049 | <0.001 | 0.019 | 0.014 | −0.347 | −0.0047 | <0.001 | 0.022 | 0.017 | −0.276 | |
| Liver metastasis | −0.0056 | <0.001 | 0.020 | 0.014 | −0.395 | −0.0055 | <0.001 | 0.023 | 0.017 | −0.324 | |
| Lung metastasis | −0.0049 | <0.001 | 0.019 | 0.014 | −0.349 | −0.0048 | <0.001 | 0.022 | 0.017 | −0.280 | |
| RNE | 0.0065 | <0.001 | 0.008 | 0.014 | 0.457 | 0.0112 | <0.001 | 0.006 | 0.017 | 0.653 | |
| Tumor size | −0.0012 | <0.001 | 0.015 | 0.014 | −0.084 | −0.0016 | <0.001 | 0.019 | 0.017 | −0.095 | |
ACME, average causal mediation effect; ADE, average direct effect; M, metastasis; N, node; Proportion, proportion of mediating effect, Proportion = ACME/total effect; RNE, regional nodes examined; T, tumor; TE, total effect.
Table 4. Causal mediation analysis for clinicopathological parameter with API-White disparities in all-cause and lung cancer-specific death, 2000–2019.
| Variables | Overall | Lung cancer | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ACME | PACME | ADE | TE | Proportion | ACME | PACME | ADE | TE | Proportion | ||
| Income | −0.0060 | <0.001 | −0.033 | −0.039 | 0.153 | −0.0069 | <0.001 | −0.035 | −0.042 | 0.163 | |
| Age | 0.0001 | 0.42 | −0.040 | −0.039 | −0.002 | 0.0001 | 0.27 | −0.043 | −0.042 | −0.003 | |
| Sex | 0.0015 | <0.001 | −0.041 | −0.039 | −0.038 | 0.0015 | <0.001 | −0.044 | −0.042 | −0.036 | |
| Primary site | −0.0001 | 0.30 | −0.039 | −0.039 | 0.002 | −0.0003 | 0.02 | −0.042 | −0.042 | 0.007 | |
| Grade | −0.0011 | <0.001 | −0.038 | −0.039 | 0.027 | −0.0024 | <0.001 | −0.040 | −0.042 | 0.056 | |
| Stage | 0.0004 | 0.19 | −0.040 | −0.039 | −0.010 | −0.0012 | 0.004 | −0.041 | −0.042 | 0.028 | |
| T | −0.0004 | 0.044 | −0.039 | −0.039 | 0.011 | −0.0012 | <0.001 | −0.041 | −0.042 | 0.028 | |
| N | −0.0001 | 0.50 | −0.039 | −0.039 | 0.003 | −0.0008 | <0.001 | −0.042 | −0.042 | 0.018 | |
| M | −0.0009 | <0.001 | −0.039 | −0.039 | 0.022 | −0.0012 | <0.001 | −0.041 | −0.042 | 0.028 | |
| Surgery | 0.0016 | <0.001 | −0.041 | −0.039 | −0.039 | −0.0006 | 0.15 | −0.042 | −0.042 | 0.015 | |
| Radiotherapy | −0.0019 | <0.001 | −0.038 | −0.039 | 0.048 | −0.0028 | <0.001 | −0.040 | −0.042 | 0.067 | |
| Chemotherapy | 0.0009 | <0.001 | −0.040 | −0.039 | −0.023 | 0.0006 | 0.004 | −0.043 | −0.042 | −0.015 | |
| Bone metastasis | −0.0085 | <0.001 | −0.031 | −0.039 | 0.215 | −0.0103 | <0.001 | −0.032 | −0.042 | 0.243 | |
| Brain metastasis | −0.0082 | <0.001 | −0.031 | −0.039 | 0.208 | −0.0099 | <0.001 | −0.033 | −0.042 | 0.234 | |
| Liver metastasis | −0.0090 | <0.001 | −0.030 | −0.039 | 0.228 | −0.0108 | <0.001 | −0.032 | −0.042 | 0.254 | |
| Lung metastasis | −0.0081 | <0.001 | −0.031 | −0.039 | 0.204 | −0.0097 | <0.001 | −0.033 | −0.042 | 0.229 | |
| RNE | 0.0013 | <0.001 | −0.041 | −0.039 | −0.032 | 0.0002 | 0.44 | −0.043 | −0.042 | −0.006 | |
| Tumor size | −0.0041 | <0.001 | −0.035 | −0.039 | 0.103 | −0.0053 | <0.001 | −0.037 | −0.042 | 0.125 | |
ACME, average causal mediation effect; ADE, average direct effect; M, metastasis; N, node; Proportion, proportion of mediating effect, Proportion = ACME/total effect; RNE, regional nodes examined; T, tumor; TE, total effect.
Table 5. Hazard ratios for all-cause and cause-specific death among Black and API compared with White patients by clinicopathological parameters, 2000–2019.
| Variables | Black vs. White [hazard ratio (95% CI)] | API vs. White [hazard ratio (95% CI)] | |||||
|---|---|---|---|---|---|---|---|
| Overall | Lung cancer | Causes other than lung cancer | Overall | Lung cancer | Causes other than lung cancer | ||
| Sex | |||||||
| Male | 1.08 (1.07–1.10) | 1.06 (1.04–1.07) | 1.15 (1.11–1.19) | 0.92 (0.92–0.93) | 0.90 (0.89–0.91) | 0.88 (0.86–0.90) | |
| Female | 1.08 (1.07–1.10) | 1.05 (1.04–1.07) | 1.17 (1.13–1.21) | 0.88 (0.87–0.89) | 0.86 (0.85–0.87) | 0.82 (0.80–0.84) | |
| Age, years | |||||||
| <60 | 1.17 (1.15–1.19) | 1.15 (1.13–1.17) | 1.47 (1.40–1.55) | 0.90 (0.88–0.91) | 0.88 (0.87–0.89) | 0.86 (0.83–0.90) | |
| 60–69 | 1.12 (1.10–1.14) | 1.10 (1.08–1.12) | 1.29 (1.23–1.34) | 0.88 (0.87–0.89) | 0.86 (0.85–0.87) | 0.82 (0.80–0.85) | |
| 70–79 | 1.12 (1.10–1.14) | 1.09 (1.07–1.12) | 1.09 (1.07–1.12) | 0.92 (0.91–0.93) | 0.89 (0.88–0.90) | 0.88 (0.85–0.90) | |
| ≥80 | 1.12 (1.08–1.16) | 1.06 (1.02–1.10) | 1.22 (1.13–1.31) | 0.95 (0.93–0.96) | 0.92 (0.90–0.93) | 0.89 (0.86–0.93) | |
| Income | |||||||
| <$50,000 | 1.04 (1.01–1.06) | 1.00 (0.98–1.03) | 1.08 (1.03–1.14) | 0.92 (0.85–0.98) | 0.90 (0.83–0.97) | 0.90 (0.76–1.06) | |
| $50,000–$74,999 | 1.08 (1.06–1.09) | 1.05 (1.04–1.07) | 1.16 (1.12–1.20) | 0.93 (0.92–0.94) | 0.91 (0.90–0.92) | 0.90 (0.87–0.92) | |
| $75,000+ | 1.09 (1.07–1.12) | 1.07 (1.05–1.09) | 1.11 (1.06–1.17) | 0.92 (0.92–0.93) | 0.90 (0.89–0.91) | 0.89 (0.87–0.90) | |
| Primary site | |||||||
| Upper lobe | 1.11 (1.10–1.13) | 1.08 (1.07–1.10) | 1.16 (1.13–1.21) | 0.91 (0.90–0.92) | 0.89 (0.88–0.90) | 0.87 (0.85–0.89) | |
| Middle lobe | 1.10 (1.05–1.16) | 1.07 (1.01–1.13) | 1.15 (1.02–1.29) | 0.89 (0.87–0.92) | 0.87 (0.84–0.90) | 0.86 (0.80–0.92) | |
| Lower lobe | 1.09 (1.07–1.12) | 1.07 (1.04–1.10) | 1.16 (1.10–1.22) | 0.92 (0.91–0.93) | 0.90 (0.88–0.91) | 0.85 (0.82–0.87) | |
| Grade | |||||||
| I | 1.18 (1.10–1.25) | 1.19 (1.10–1.28) | 1.05 (0.93–1.19) | 0.89 (0.96–0.92) | 0.91 (0.87–0.94) | 0.76 (0.71–0.82) | |
| II | 1.16 (1.13–1.20) | 1.15 (1.12–1.19) | 1.11 (1.04–1.17) | 0.91 (0.89–0.92) | 0.89 (0.87–0.90) | 0.81 (0.78–0.84) | |
| III | 1.09 (1.07–1.11) | 1.06 (1.04–1.08) | 1.10 (1.05–1.16) | 0.95 (0.94–0.96) | 0.92 (0.91–0.94) | 0.90 (0.87–0.93) | |
| IV | 1.01 (0.96–1.06) | 0.98 (0.93–1.03) | 0.99 (0.86–1.12) | 0.95 (0.2–0.98) | 0.93 (0.89–0.96) | 0.98 (0.90–1.07) | |
| Tumor size, cm | |||||||
| ≤7 | 1.11 (1.09–1.12) | 1.09 (1.07–1.10) | 1.15 (1.12–1.19) | 0.91 (0.90–0.92) | 0.89 (0.89–0.90) | 0.85 (0.83–0.87) | |
| >7 | 1.04 (0.66–1.64) | 0.89 (0.54–1.48) | 3.28 (0.94–11.5) | 0.78 (0.53–1.14) | 0.76 (0.50–1.15) | 1.21 (0.41–3.64) | |
| Stage | |||||||
| I | 1.03 (0.99–1.07) | 1.04 (0.99–1.10) | 0.96 (0.90–1.02) | 0.81 (0.80–0.84) | 0.82 (0.79–0.84) | 0.74 (0.72–0.77) | |
| II | 1.01 (0.95–1.06) | 0.99 (0.93–1.05) | 0.93 (0.84–1.05) | 0.93 (0.90–0.96) | 0.92 (0.88–0.96) | 0.90 (0.84–0.96) | |
| III | 1.02 (1.00–1.05) | 1.00 (0.98–1.03) | 1.09 (1.02–1.16) | 0.90 (0.88–0.91) | 0.88 (0.86–0.89) | 0.85 (0.81–0.89) | |
| IV | 1.01 (0.99–1.02) | 1.00 (0.98–1.02) | 1.11 (1.06–1.16) | 0.84 (0.83–0.85) | 0.83 (0.82–0.84) | 0.77 (0.75–0.79) | |
| T stage | |||||||
| T1 | 1.09 (1.05–1.13) | 1.08 (1.03–1.12) | 1.03 (0.97–1.10) | 0.85 (0.83–0.87) | 0.84 (0.82–0.86) | 0.78 (0.74–0.81) | |
| T2 | 1.05 (1.03–1.08) | 1.03 (1.00–1.06) | 1.08 (1.02–1.14) | 0.88 (0.87–0.90) | 0.87 (0.85–0.88) | 0.84 (0.81–0.87) | |
| T3 | 1.03 (1.00–1.06) | 1.02 (0.98–1.05) | 1.11 (1.02–1.21) | 0.91 (0.89–0.93) | 0.90 (0.88–0.92) | 0.87 (0.82–0.92) | |
| T4 | 1.01 (0.99–1.03) | 0.99 (0.97–1.01) | 1.23 (1.06–1.19) | 0.89 (0.88–0.90) | 0.88 (0.86–0.89) | 0.87 (0.84–0.91) | |
| N stage | |||||||
| N0 | 1.16 (1.13–1.18) | 1.15 (1.12–1.19) | 1.09 (1.04–1.14) | 0.90 (0.89–0.92) | 0.89 (0.88–0.91) | 0.81 (0.80–0.84) | |
| N1 | 1.08 (1.04–1.13) | 1.06 (1.01–1.11) | 1.05 (0.94–1.16) | 0.89 (0.87–0.92) | 0.88 (–.85–0.90) | 0.86 (0.81–0.93) | |
| N2 | 0.99 (0.97–1.01) | 0.97 (0.95–0.99) | 1.07 (1.01–1.13) | 0.88 (0.87–0.89) | 0.86 (0.85–0.878) | 0.84 (0.81–0.87) | |
| N3 | 1.00 (0.97–1.03) | 1.00 (0.97–1.04) | 1.18 (1.07–1.29) | 0.85 (0.83–0.86) | 0.84 (0.82–0.86) | 0.76 (0.72–0.81) | |
| M stage | |||||||
| M0 | 1.10 (1.08–1.12) | 1.09 (1.07–1.11) | 1.05 (1.01–1.09) | 0.89 (0.88–0.90) | 0.88 (0.86–0.89) | 0.82 (0.80–0.84) | |
| M1 | 1.01 (0.99–1.02) | 1.00 (0.98–1.02) | 1.11 (1.06–1.16) | 0.84 (0.83–0.85) | 0.83 (0.82–0.84) | 0.77 (0.75–0.79) | |
| Bone metastasis | |||||||
| No | 1.12 (1.09–1.14) | 1.11 (1.10–1.13) | 1.16 (1.11–1.20) | 0.90 (0.89–0.91) | 0.90 (0.89–0.91) | 0.82 (0.80–0.84) | |
| Yes | 1.07 (1.04–1.10) | 1.07 (1.04–1.11) | 1.22 (1.11–1.33) | 0.80 (0.79–0.81) | 0.79 (0.78–0.81) | 0.73 (0.69–0.77) | |
| Brain metastasis | |||||||
| No | 1.10 (1.08–1.12) | 1.09 (1.07–1.11) | 1.17 (1.12–1.22) | 0.90 (0.89–0.91) | 0.90 (0.89–0.91) | 0.83 (0.81–0.85) | |
| Yes | 1.02 (0.99–1.06) | 1.03 (0.99–1.07) | 1.05 (0.94–1.17) | 0.81 (0.79–0.83) | 0.80 (0.79–0.82) | 0.73 (0.68–0.77) | |
| Liver metastasis | |||||||
| No | 1.12 (1.10–1.13) | 1.11 (1.10–1.13) | 1.16 (1.12–1.21) | 0.91 (0.90–0.92) | 0.91 (0.90–0.92) | 0.83 (0.81–0.86) | |
| Yes | 1.05 (1.00–1.09) | 1.05 (1.00–1.10) | 1.18 (1.05–1.32) | 0.84 (0.82–0.86) | 0.83 (0.81–0.85) | 0.74 (0.69–0.80) | |
| Lung metastasis | |||||||
| No | 1.10 (1.08–1.12) | 1.09 (1.07–1.11) | 1.16 (1.11–1.20) | 0.89 (0.89–0.90) | 0.87 (0.88–0.90) | 0.82 (0.80–0.85) | |
| Yes | 0.98 (0.95–1.02) | 0.98 (0.94–1.01) | 1.09 (0.99–1.21) | 0.84 (0.83–0.86) | 0.84 (0.82–0.86) | 0.76 (0.72–0.82) | |
| Surgery | |||||||
| No | 0.99 (0.98–1.00) | 0.97 (0.96–0.98) | 1.06 (1.03–1.09) | 0.89 (0.88–0.90) | 0.87 (0.87–0.88) | 0.85 (0.83–0.86) | |
| Yes | 1.01 (0.98–1.04) | 1.00 (0.97–1.04) | 0.93 (0.89–0.98) | 0.88 (0.86–0.89) | 0.87 (0.86–0.89) | 0.78 (0.76–0.81) | |
| Regional nodes examined | |||||||
| 0 | 1.01 (0.99–1.02) | 0.98 (0.97–0.99) | 1.10 (1.06–1.13) | 0.90 (0.89–0.91) | 0.88 (0.87–0.89) | 0.87 (0.85–0.89) | |
| 1–15 | 1.03 (1.00–1.06) | 1.02 (0.99–1.06) | 0.94 (0.89–0.99) | 0.88 (0.86–0.89) | 0.86 (0.85–0.88) | 0.78 (0.76–0.81) | |
| ≥16 | 0.95 (0.88–1.03) | 0.95 (0.86–1.05) | 0.84 (0.72–0.97) | 0.80 (0.86–0.94) | 0.90 (0.86–0.95) | 0.80 (0.74–0.87) | |
| Radiotherapy | |||||||
| No | 1.14 (1.12–1.15) | 1.10 (1.09–1.12) | 1.22 (1.18–1.26) | 0.91 (0.90–0.92) | 0.88 (0.88–0.89) | 0.86 (0.84–0.88) | |
| Yes | 1.01 (1.00–1.03) | 0.99 (0.98–1.01) | 1.02 (0.98–1.06) | 0.92 (0.91–0.92) | 0.90 (0.89–0.91) | 0.87 (0.85–0.90) | |
| Chemotherapy | |||||||
| No | 1.18 (1.17–1.20) | 1.16 (1.14–1.18) | 1.22 (1.18–1.26) | 0.93 (0.92–0.94) | 0.90 (0.89–0.91) | 0.86 (0.85–0.86) | |
| Yes | 0.98 (0.97–1.00) | 0.96 (0.95–0.98) | 1.06 (1.02–1.11) | 0.88 (0.87–0.88) | 0.86 (0.85–0.87) | 0.85 (0.83–0.87) | |
Grade I, well differentiated; Grade II, moderately differentiated; Grade III, poorly differentiated; Grade IV, undifferentiated. API, Asian or Pacific Islander; CI, confidence interval; M, metastasis; N, node; T, tumor.
Discussion
In our study, we are the first to explore trends in all-cause and cause-specific deaths in lung cancer patients across racial groups in the United States over the past 20 years. Our findings provide the most comprehensive and sustained overview of racial disparities and trends in lung cancer deaths in the United States. Black and AIAN lung cancer patients had a persistently worse clinical outcome compared to White patients, while we found a perpetuation of a better prognosis in API patients. In addition, we found that household income, surgery status, and regional nodes examined were the main factors contributing to the mortality difference between Black and White. Household income and distant metastases (bone, liver, lung and brain) are the main factors that lead to the mortality difference between API and White. The current findings may provide additional theoretical basis for addressing racial inequities in lung cancer and promoting health equity.
Racial disparities in lung cancer deaths have been identified by a previous study (13). Similarly, our study indicated higher all-cause mortality and cause-specific mortality in Black and AIAN lung cancer patients versus White patients. In addition, we reveal for the first time that every race has not enjoyed the benefits of the gradual decline in all-cause mortality among lung cancer patients equitably, but interestingly, the largest decline has been among the API patients. We found that between 2000 and 2019, all-cause mortality declined more among API patients than among White patients, contributing to a widening of absolute and relative disparities between API and White patients. Although there was no statistically significant trend in the change of the absolute disparities in all-cause mortality between Black and White patients during 2000–2019, a significant trend in the change of relative disparities was found, highlighting the methodological importance of reporting both absolute and relative measures of disparities to provide a clear picture of health disparity change across races. Notably, although the absolute disparities of all-cause deaths between White and AIAN was small during the study period, the most recent years of data (2015–2019) showed that AIAN had a 1.22 times higher risk of all-cause death than White patient in lung cancer, indicating that the relative disparity remains large, and much still need to be done. Although the economy and culture of the United States are constantly developing, racial differences and discrimination may still exist, resulting in the healthcare received by blacks and AIANs not being improved, thus leading to the occurrence of this trend. Despite being based on different databases and time periods, two recent studies also indicated that Black patients had the highest mortality rates, especially Black men (14,15). However, these two studies, based on the CDC Wide-ranging Online Data for Epidemiologic Research (WONDER) database, showed that White patients had the second highest mortality rate after Black patients, with the lowest rates observed in AIAN and API patients, which differs from our findings. This discrepancy may be attributed to differences in the study populations and research strategies between the two databases. The WONDER database emphasizes mortality statistics collected from death certificates, whereas the SEER database follows patients from the time of diagnosis until death.
Approximately 12% of lung cancer patients died from causes other than lung cancer, a factor that should not be overlooked. The assessment of racial differences in all-cause deaths may mask substantial differences in deaths from some specific causes. Black patients had a higher risk of all-cause death compared with White patients in lung cancer, however, Black patients had a lower risk of COPD-cause death compared with White patients. Thus, distinguishing racial differences based on cause of death could provide more precise information, contributing to more individualized therapy. Though the absolute disparities of all-cause deaths between White and AIAN was similar, we first identified widening relative disparities but diminishing absolute disparities of death causes other than lung cancer between White and AIAN patients. These results suggest that anti-lung cancer efforts cannot be undertaken in isolation and ethnicity, as well as other comorbidities/diseases, should also be taken into account. Equality in cancer treatment will only be possible if efforts are made to control cardiovascular disease, COPD and other diseases across all races.
Surgery remains the primary therapy approach for the early stages of lung cancer. Neroda et al. found that Black lung cancer patients were nearly twice as likely as White patients to receive delayed surgery (16). Moreover, White patients were more likely to receive gold standard surgery for early-stage non-small cell lung cancer versus Black patients (17). The effect of surgery status on the mortality difference between Black and White patients with lung cancer has important analytical power (18). Similarly, our result revealed that surgical rate of Black patients with lung cancer was significantly lower than White patients (19% vs. 26%). Moreover, surgery status exerts the largest effect on Black-White disparities in lung cancer-specific mortality. Remarkably, surgery itself could be affected by various factors, including socioeconomic status, cancer awareness, health insurance, access to health care, healthcare provider biases, and biological factors (19-21). Among the lung cancer patients, lower socioeconomic status among Black patients was associated with an increasing risk of having advance disease and lower rate of receiving surgery than White patients, leading to racial disparity in mortality (22,23). Lack of insurance in Black race is correlated with deferring surgical therapy for NSCLC, which may also result in racial disparity in mortality (24). Thus, the US Preventive Services Task Force suggested that targeted intervention strategies are recommended to increase lung cancer screening in Blacks (25). In lung cancer, the expansion of Medicaid and increasing proportion of insurance are correlated with an increased rate of early-stage cancer diagnosis, which increases the likelihood of surgery and thus may reduce racial disparities in mortality (26). Our study also found that API patients had a higher prevalence of distant diseases, including brain metastasis, bone metastasis and liver metastasis, which is consistent with the results of previous studies (27,28). However, the clinical outcome of API lung cancer patients is relatively better than White patients, for reasons that are unclear. Therefore, if the incidence of distant metastases can be reduced in API patients, its mortality disparity with White patients will be more pronounced than at present. Although low-dose computed tomography (CT) screening can significantly reduce mortality in lung cancer patients, especially for Black patients, lower adherence was found in Black patients than White patients, which is one reason why racial disparities in mortality are far from elimination (29).
Race continues to face more severe multiple barriers to access to quality cancer care, including therapy delays, absence of specific treatment guidelines, and implicit bias (30). Lobectomy could improve the clinical outcome of lung cancer. Our result found a persistently lower rate in receiving surgery in Black and AIAN patients versus White patients, which may at least partly result in racial mortality disparity. Unequal access to care resulted in a difference in 5-year relative survival rate for localized lung cancer in different races (46% for AIAN vs. 60% for White) (31). However, racial differences are not insurmountable. Increasing evidence demonstrated the elimination of racial prognostic disparity in cancer, including lung cancer and prostate cancer, when they had equitable access to standard treatment (32,33). All in all, providing all lung cancer patients with equitable and quality care is indispensable to addressing racial disparities.
Phelan et al. suggested structural racism as root cause of racial health inequities (30). Structural racism is defined as the totality of ways in which societies foster racial discrimination, through mutually reinforcing inequitable systems composed of education, employment, income, health care, etc., which in turn can reinforce discriminatory beliefs, values, and distribution of resources, leading to the risk of adverse health outcomes and perpetuate racial group inequity (34). A framework aimed at eliminating racial disparities and achieving health equity, constructed by American Cancer Society, demonstrated that health-related disparities stem from social structural (35). Studies have shown that Black and AIAN patients living in rural areas lag behind White patients in early diagnosis, treatment, and clinical outcomes due to poor living conditions, low income, inadequate education, and lack of access to quality care (36-38). In our study, the data also suggested lower household income and lack of standardized therapy in Black and AIAN patients versus White patients. Therefore, to eliminate racial disparities and achieve health equity, there is an urgent need to eliminate unfair institutions and structural racism.
The role of genetic and biological determinants in influencing racial disparities should also not be overlooked. Compared with non-Hispanic Whites, African Americans/Blacks patients had a higher genomic instability, more aggressive molecular features and higher PTPRT and JAK2 mutation rate (39). Previous study showed that Black and API lung cancer patients had a higher stage than White patients (28). Another study demonstrated a younger age and higher likelihood of progression to a metastatic state in Black patients compared with White patients in lung cancer (40). Notably, lifestyle interventions (such as smoking, alcohol consumption, diet) can still reduce the incidence and mortality in high-risk lung cancer patients (5,41). Interestingly, these lifestyles are correlated with the risk of COPD and heart diseases. What we should not ignore is that the same lifestyles had different influences among different races. Here, we appeal for improving the prognosis and health equity in lung cancer patients by removing adverse behavioral intervention.
Several strengths could be found in our study. As far as we know, the current investigation is the first one to explore trends of racial disparities in the all-cause and cause-specific death in different racial lung cancer patients in the US over time. A large enough cohort of patients, a detailed races breakdown, and an extremely long follow-up period make it possible to fully and objectively elucidate the correlation between race and the prognosis of lung cancer patients. Moreover, absolute and relative quantitative measures provide a more objective description of trends in racial disparities. Our findings also shed light on the main factors driving racial disparities, providing more specific directions for subsequent intervention strategies.
Some limitations should not be ignored. The absence of some data may have affected our results to some extent. Moreover, the absence of individual-level socioeconomic and lifestyle data, including insurance status, household income, and smoking, limits further exploration of the socioeconomic factors that affect racial disparities. It would be better to obtain the data about smoking history for patients and the number of pack years for each race, as the outcomes in blacks were worse even with adjusted smoking history. We could not obtain data about the lung cancer screening rates and differences between different races, which may affect our results. We only quantified racial disparities in lung cancer in the US, which is not representative of racial disparities in lung cancer patients around the world.
Conclusions
In conclusion, our findings reveal persistent racial disparities among lung cancer patients, providing a theoretical basis for interventions to eliminate health disparities.
Supplementary
The article’s supplementary files as
Acknowledgments
None.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments.
Footnotes
Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-333/rc
Funding: This study was supported by key projects of the Sichuan Provincial Department of Science and Technology (No. 2024YFFK0382).
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-333/coif). The authors have no conflicts of interest to declare.
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