Abstract
Background
Racial/ethnic minority groups, including Hispanic Americans (HAs) and Native Americans (NAs), have a heavier burden of kidney cancer than European Americans (EAs). We investigated variations in clinical characteristics of HA and NA renal cell carcinoma (RCC) patients who were previously underrepresented.
Materials and Methods
Clinical records of 294 RCC patients (151 EAs, 95 HAs, 22 NAs, and 26 others) without prior diagnosis of cancer were reviewed. Logistic regression analysis was performed to understand patients’ clinical characteristics.
Results
HA had about 5 years younger average age at diagnosis than EAs (55.8 vs. 60.5) and an almost 3-fold increased odds of diagnosis before age 50 years (OR 2.77, 95% C.I.: 1.39–5.54). Mean age of diagnosis among NAs was 49.7, and NAs had an over 6-fold higher odds of diagnosis at a younger age (OR 6.23, 95% C.I.: 2.00–19.46). Clear cell RCC (ccRCC) was more common in HAs and NAs than EAs. Over 90% of HA patients had ccRCC, while only 78.8% of EA patients had ccRCC. HAs had increased odds of diagnosis with ccRCC compared to EAs (OR 2.79, 95% C.I.: 1.15–6.80). Among HAs, older patients and patients who spoke Spanish as their primary language were more likely to have advanced stage RCC at diagnosis (OR 10.48, 95% C.I.: 1.69–64.89 and OR 4.61, 95% C.I.: 1.38–15.40).
Conclusion
HA and NA RCC patients had different clinical characteristics from EA patients. It is necessary to better understand the clinical characteristics of these underserved HA and NA populations with high kidney cancer burden.
Keywords: Kidney Cancer, Health Disparities, Hispanic Americans, Native Americans
MicroAbstract
Variations in clinical characteristics in underrepresented renal cell carcinoma patients were investigated. This study included 294 patients and showed Hispanic and Native American patients were more likely to be diagnosed with clear cell subtype and at a younger age than European American patients. Older Hispanic patients who spoke Spanish were more likely to have advanced stage renal cell carcinoma.
Introduction
Racial/ethnic minority groups, including African Americans (AAs), Hispanic Americans (HAs), and Native Americans (NAs), have heavier burden of kidney cancer based on higher incidence and mortality rates compared to European Americans (EAs) of non-Hispanic origin1,2. However, it remains unknown why this racial disparity exists. HAs and NAs are underrepresented in clinical and molecular genomic studies of renal cell carcinoma (RCC), and clinical characteristics of RCC among these ethic groups are not well understood3. These differences raise the questions of whether racial/ethnic groups have more aggressive forms of RCC and genetic predisposition, and whether other issues related to health care access and lifestyle factors contribute to these disparities.
Previous studies have shown that various risk factors, including male gender, chronic kidney disease (CKD), smoking, hypertension, and excess body mass index (BMI), predispose to RCC4. One study also indicated that HAs appeared to be diagnosed at younger ages, have greater comorbidities, and present more frequently with clear cell renal cell carcinoma (ccRCC) compared to EA patients5. Furthermore, it is well known that in the United States, access to healthcare varies significantly by racial/ethnic groups, and this may explain the differences in cancer-related outcomes due to treatment barriers6–9.
We sought to determine and compare the clinical and pathologic characteristics among HA, NA, AA and EA RCC patients who were treated at the University of Arizona College of Medicine/Banner-University Medical Center to better understand the disease burden differences between these racial/ethnic groups in Arizona. Arizona is uniquely located to address kidney cancer health disparities with a good representation of HAs and NAs. This study particularly focuses on HAs, who are the largest racial/ethnic minority groups in Arizona.
Materials and Methods
Samples
After Institutional Review Board approval, the clinical information of RCC patients, who underwent robotic, laparoscopic or open, partial or radical nephrectomy at the University of Arizona College of Medicine/Banner-University Medical Center, Tucson between 2010 and 2017 (n=427) was reviewed. A total of 294 patients who were diagnosed with RCC were included to understand the patient’s clinical characteristics. We excluded 133 patients who did not have a malignant tumor (but a benign renal mass was removed), who had kidney cancer other than RCC, and who had a prior diagnosis of kidney cancer or other types of cancer (Figure 1). Patient’s demographic (age at surgery, gender, and race/ethnicity), medical history, surgical, and clinical information (histological subtype, stage at diagnosis, Fuhrman Grade, tumor size, and presence of necrosis) was obtained from their electronic medical record. The Stage, Size, Grade, and Necrosis (SSIGN) score, a composite score of these 4 clinical assessment measures10,11, was calculated.
Figure 1. Study Flow Diagram.
Abbreviation: RCC = renal cell carcinoma.
Statistical Analysis
Independent sample T-test and Chi-squared test were used to understand patients’ characteristics. Unconditional logistic regression analysis was performed to identify demographic and clinical factors associated with diagnosis with early age, advanced RCC, diagnosis with ccRCC, and undergoing radical nephrectomy adjusting for relevant variables, such as gender, BMI, comorbidity, and health insurance type. In the final adjusted models, statistically non-significant variables (P>0.10) that did not affect the associations (ORs) between variables of our interest and outcomes were not included. Patients with metastasis at diagnosis (n=34) were excluded for analysis of nephrectomy type (radical vs. partial nephrectomy). Sub-analysis with HA patients were performed to identify demographic and clinical factors associated with diagnosis with advanced stage RCC and undergoing radical nephrectomy. Statistical analysis was performed using SPSS v.25 (IBM, Armonk, NY).
Results
The HA (30.3%) and NA (7.7%) patients included in our study reflects Arizona’s racial/ethnic composition (Table 1). Compared to EAs, HA and NA patients were diagnosed with RCC at a younger age (P<0.001). Mean age at diagnosis of HA and NA patients were 55.8 and 49.7 years, while EA patients had mean age of 60.5 years. NA patients had higher BMI than EA patients, and 77.3% of NA patients were obese. Despite large number patients who were diagnosed at younger ages, only 6 patients, 4 EAs, 1 HAs, and 1 NAs, self-reported having family history of kidney cancer. Diabetes was more common in HA (45.6%) and NA (54.5%) patients compared to EA (21.7%) patients. History of cigarette smoking was less common in HA and NA patients. Although it was not statistically significant, a higher proportion of HA and NA patients had public health insurance, such as Medicare and other public health insurance, compared to EA patients.
Table 1.
RCC Patient Characteristics at BUMCT (n=294)
| EAs (n=151) | HAs (n=95) | NAs (n=22) | AAs (n=9) | Others (n=17) | |
|---|---|---|---|---|---|
| Age at surgery, mean (SD) | 60.5 (12.0) | 55.8 (11.9)** | 49.7 (13.6)*** | 57.2 (6.5) | 60.6 (11.0) |
| Age category, n (%) | |||||
| <50 | 30 (19.9) | 29 (30.5) | 11 (50.0) | 1 (111) | 2 (11.8) |
| 50–64 | 58 (38.4) | 41 (43.2) | 10 (45.5) | 7 (77.8) | 10 (58.8) |
| ≥65 | 63 (41.7) | 25 (26.3) | 1 (4.5) | 1 (111) | 5 (29.4) |
| Gender, n (%) | |||||
| Male | 102 (67.5) | 56 (59.6) | 15 (68.2) | 6 (66.7) | 12 (75.0) |
| Female | 49 (32.5) | 38 (40.4) | 7 (31.8) | 3 (33.3) | 4 (25.0) |
| Body Mass Index (BMI), mean (SD) | 30.7 (7.2) | 31.9 (7.3) | 35.2 (7.1)** | 31.5 (7.7) | 29.6 (5.7) |
| BMI Category, n (%) | |||||
| Normal | 28 (19.3) | 12 (12.8) | 1 (4.5) | 1 (12.5) | 2 (14.3) |
| Overweight | 44 (30.3) | 25 (26.6) | 4 (18.2) | 3 (37.5) | 5 (35.7) |
| Obese | 73 (50.3) | 57 (60.6) | 17 (77.3) | 4 (50.0) | 7 (50.0) |
| Smoking, n (%) | |||||
| No | 76 (51.4) | 66 (69.5) | 16 (72.7) | 5 (55.6) | 10 (58.8) |
| Yes | 72 (48.6) | 29 (30.5)** | 6 (27.3) | 4 (44.4) | 7 (41.2) |
| Comorbidities | |||||
| Hypertension, n (%) | 89 (61.4) | 62 (66.0) | 13 (59.1) | 9 (100.0) | 10 (58.8) |
| Diabetes, n (%) | 31 (21.7) | 41 (45.6)*** | 12 (54.5)** | 3 (33.3) | 8 (47.1)* |
| Chronic Kidney Disease, n (%) | 8 (5.8) | 8 (8.8) | 2 (10.0) | 3 (37.5)*** | 1 (6.3) |
| End Stage Kidney Disease, n (%) | 2 (25.0) | 3 (37.5) | 1 (50.0) | 2 (66.7) | 1 (100.0) |
| Insurance Type, n (%) | |||||
| Private | 38 (30.9) | 19 (22.6) | 3 (18.8) | 3 (33.3) | 0 (0.0) |
| Medicare | 18 (14.6) | 39 (46.4) | 7 (43.8) | 2 (22.2) | 3 (42.9) |
| Medicaid | 51 (41.5) | 20 (23.8) | 1 (6.3) | 3 (33.3) | 2 (28.6) |
| Other Public Insurance | 7 (5.7) | 1 (1.2) | 4 (25.0) | 0 (0.00) | 0 (0.00) |
| No Insurance | 9 (7.3) | 5 (6.0) | 1 (6.3) | 1 (111) | 2 (28.6) |
| Family History of Kidney Cancer, n (%) | 4 (2.6) | 1 (11) | 1 (4.5) | 0 (0.0) | 0 (0.0) |
| Surgical Approach, n (%) | |||||
| Robotic | 48 (35.8) | 33 (39.3) | 5 (23.8) | 3 (37.5) | 8 (61.5) |
| Laparoscopic | 16 (11.9) | 13 (15.5) | 3 (14.3) | 2 (25.0) | 0 (0.0) |
| Open | 70 (52.2) | 38 (45.2) | 13 (61.9) | 3 (37.5) | 5 (38.5) |
| Nephrectomy Type, n (%) | |||||
| Partial | 85 (63.4) | 47 (56.0) | 13 (61.9) | 2 (25.0) | 10 (76.9) |
| Radical | 49 (36.6) | 37 (44.0) | 8 (38.1) | 6 (75.0)* | 3 (23.1) |
| Histology, n (%) | |||||
| Clear Cell | 119 (78.8) | 88 (92.6)* | 19 (86.4) | 7 (77.8) | 9 (52.9) |
| Papillary | 19 (12.6) | 4 (4.2) | 0 (0.0) | 1 (111) | 6 (35.3) |
| Chromophobe | 6 (4.0) | 2 (2.1) | 1 (4.5) | 1 (11) | 0 (0.0) |
| Other | 7 (4.6) | 1 (11) | 2 (9.1) | 0 (0.0) | 2 (11.8) |
| Stage, n (%) | |||||
| I or II | 97 (64.7) | 54 (56.8) | 13 (59.1) | 2 (22.2) | 10 (58.8) |
| III or IV | 53 (35.3) | 41 (42.2) | 9 (40.9) | 7 (77.8)* | 7 (41.2) |
| Metastasis at Presentation, n (%) | |||||
| No | 137 (88.7) | 84 (88.4) | 21 (95.5) | 8 (88.9) | 13 (76.5) |
| Yes | 17 (11.3) | 11 (11.6) | 1 (4.5) | 1 (111) | 4 (23.5) |
| Necrosis, n (%) | |||||
| Not Present | 89 (62.7) | 69 (73.4) | 15 (71.4) | 5 (55.6) | 12 (70.6) |
| Present | 53 (37.3) | 25 (26.6) | 6 (28.6) | 3 (37.5) | 5 (29.4) |
| Fuhrman Grade, n (%) | |||||
| 1 or 2 | 51 (43.2) | 43 (49.4) | 11 (57.9) | 3 (33.3) | 3 (33.3) |
| 3 or 4 | 67 (56.8) | 44 (50.6) | 8 (42.1) | 4 (57.1) | 6 (66.7) |
| Tumor Size, median (IQR) SSIGN, n (%) | 4.5 (4.5) | 5.0 (4.4) | 4.3 (2.2) | 6.3 (4.7) | 3.0 (5.9) |
| Low (<3) | 52 (46.4) | 46 (54.1) | 9 (50.0) | 1 (16.7) | 4 (44.4) |
| Medium (3–5) | 34 (30.4) | 25 (29.4) | 7 (38.9) | 3 (50.0) | 2 (22.2) |
| High (≥6) | 26 (23.2) | 14 (16.5) | 2 (11.1) | 2 (33.3) | 3 (33.3) |
P<0.05,
P<0.01, and
P<0.001 comparing to EAs. Others include Asian Americans, mixed-race individuals, and patients with unknown race/ethnicity. Patients with metastasis at diagnosis were not included for analysis of surgical approach and nephrectomy type. Fuhrman Grade is only for ccRCC.
A RCC histologic subtype, ccRCC, was more common in HAs and NAs than EAs. Over 90% of HA patients had ccRCC, while only 78.8% of EA patients had ccRCC. ccRCC was also common among NA patients (86.4%). AA, HA and NA patients tended to be diagnosed with advanced stage RCC (Stage III or IV). A significantly higher proportion of AA patients (77.8%) were diagnosed with advanced stage RCC and were more likely to receive radical nephrectomy than EA patients. Although not statistically significant, a higher proportion of HA and NA patients were diagnosed with advanced stage RCC when compared to EAs. However, compared to HA and NA patients, a higher proportion of EA patients had high grade (Fuhrman Grade 3 or 4) ccRCC than HA and NA patients (56.8% in EA. vs. 50.6% and 42.1% respectively in HAs and NAs) as well as high SSIGN score (23.2% in EA vs. 16.5% and 11.1% respectively in HAs and NAs). These differences were not statistically significant. There were 34 patients (11.6%) who had metastatic RCC at diagnosis, and we did not observe statistically significant difference in frequency of metastatic RCC across racial/ethnic groups.
We performed logistic regression analyses to identify risk factors for diagnosis of RCC at a younger age (<50), and race/ethnicity and obesity were independently associated with an increased odds of diagnosis at younger age (Table 2). HA had almost a 3-fold increased odds of diagnosis before age 50 years (OR 2.77, 95% C.I.: 1.39–5.54), and NAs had more than 6-fold higher odds of diagnosis at a younger age (OR 6.23, 95% C.I.: 2.00–19.46). Odds of diagnosis with young age increased with BMI, and morbidly obese patients had almost a 4-fold increased odds of diagnosis with young age (OR 3.98, 95% C.I.: 1.24–12.79). Because older patients often had diabetes and hypertension, having diabetes and hypertension was associated with a decreased odds of diagnosis at younger age. A similar pattern was observed, when the analysis was performed only for patients with ccRCC.
Table 2.
Predictors of diagnosis with RCC at younger age (<50)
| All RCC | Clear Cell RCC | |||
|---|---|---|---|---|
| OR (95% C.I.) | P | OR (95% C.I.) | P | |
| Gender | ||||
| Female | Reference | 0.73 | Reference | 0.49 |
| Male | 0.89 (0.46–1.73) | 0.77 (0.37–1.61) | ||
| Race/ethnicity | ||||
| EAs | Reference | 0.002 | Reference | 0.03 |
| HAs | 2.77 (1.39–5.54) | 2.18 (1.04–4.58) | ||
| NAs | 6.23 (2.00–19.46) | 4.90 (1.41–17.11) | ||
| Others | 0.69 (0.14–3.34) | 0.49 (0.05–4.37) | ||
| BMI | ||||
| Normal | Reference | 0.04 | Reference | 0.07 |
| Overweight | 1.14 (0.41–3.12) | 0.98 (0.33–2.85) | ||
| Obese | 2.52 (0.95–6.67) | 2.38 (0.85–6.61) | ||
| Morbidly Obese | 3.98 (1.24–12.79) | 3.13 (0.93–10.76) | ||
| Family History | ||||
| No | Reference | 0.68 | Reference | 0.68 |
| Yes | 1.65 (0.16–17.20) | 1.69 (0.14–20.763) | ||
| Hypertension | ||||
| No | Reference | <0.001 | Reference | 0.001 |
| Yes | 0.29 (0.15–0.56) | 0.30 (0.15–0.62) | ||
| Diabetes | ||||
| No | Reference | 0.004 | Reference | 0.002 |
| Yes | 0.29 (0.12–0.67) | 0.23 (0.09–0.59) | ||
The model includes gender, race/ethnicity, BMI, family history, hypertension, and diabetes. AAs were included with other race/ethnicity category in this analysis, because there was no AA who was diagnosed before age 50. Statistically significant findings are bolded.
Logistic Regression analysis was performed to identify demographic and clinical characteristics associated with 1) diagnosis with advanced stage RCC, 2) diagnosis with ccRCC, and 3) undergoing radical nephrectomy rather than partial nephrectomy (Table 3). Racial/ethnic minority groups were more likely to be diagnosed with advanced stage RCC. AAs had statistically significantly higher odds of diagnosis with advanced RCC, but due to small sample size the confidence interval was large (OR 6.51, 95% C.I.: 1.28–33.02). Compared to EAs, HAs and NAs had about a 50% increased odds of being diagnosed with advanced RCC, but the associations were not significant. Insurance type was not associate with diagnosis with advanced RCC, and including insurance type and other factors did not change the association. HAs had an increased odds of diagnosis with ccRCC compared to EAs (OR 2.79, 95% C.I.: 1.15–6.80). Only factor that predicted radical nephrectomy was stage at diagnosis (OR 11.59, 95% C.I.: 5.07–26.51).
Table 3.
Predictors of diagnosis with advanced stage RCC and ccRCC as well as patients undergoing radical nephrectomy
| Advanced Stage | Clear Cell RCC | Radical Nephrectomy1 | ||||
|---|---|---|---|---|---|---|
| OR (95% C.I.) | P | OR (95% C.I.) | P | OR (95% C.I.) | P | |
| Age | ||||||
| <50 | Reference | 0.22 | Reference | 0.60 | Reference | 0.49 |
| ≥50 and <65 | 1.60 (0.85–2.98) | 0.66 (0.27–1.59) | 1.56 (0.59–4.14) | |||
| ≥62 | 1.76 (0.90–3.45) | 0.64 (0.25–1.63) | 1.92 (0.64–5.76) | |||
| Gender | ||||||
| Female | Reference | 0.89 | 0.35 | 0.30 | ||
| Male | 1.04 (0.62–1.74) | 0.66 (0.32–1.36) | 1.68 (0.69–3.77) | |||
| Race/ethnicity | 0.19 | |||||
| EAs | Reference | 0.17 | Reference | Reference | 0.24 | |
| HAs | 1.47 (0.85–2.53) | 2.79 (1.15–6.80) | 1.68 (0.71–3.98) | |||
| NAs | 1.50 (0.58–3.88) | 1.26 (0.32–4.94) | 0.46 (0.10–2.19) | |||
| AAs | 6.51 (1.28–33.02) | 0.89 (0.17–4.67) | 3.30 (0.28–38.36) | |||
| Others | 1.41 (0.32–8.92) | 0.31 (0.10–0.93) | 0.46 (0.03–6.59) | |||
| Family History | ||||||
| No | Reference | 0.54 | Reference | 0.85 | Reference | 0.12 |
| Yes | 1.68 (0.32–8.92) | 0.80 (0.08–7.59) | 9.80 (0.56–173.17) | |||
| Diabetes | ||||||
| No | Reference | 0.19 | Reference | 0.15 | ||
| Yes | 1.68 (0.78–3.64) | 0.50 (0.20–1.27) | ||||
| Stage | ||||||
| I or II | Reference | <0.001 | ||||
| III or IV | 11.59 (5.07–26.51) | |||||
additionally adjusting for BMI, surgical year, and insurance type. Patients with metastasis at diagnosis were not included for analysis of nephrectomy type. Significant finds are shown with bolded letters.
Analysis was performed among HA patients to further understand their demographic characteristics related to their diagnosis and surgical care (Table 4). 53 (55.8%) of HA patients spoke English as a primary language, while 30 (31.6%) spoke Spanish as their primary language. Older HAs and HAs who spoke Spanish were more likely to have advanced stage RCC diagnosis (OR 10.48, 95% C.I.: 1.69–64.89 and OR 4.61, 95% C.I.: 1.38–15.40). In unadjusted model, HAs who used Spanish as their primary language had an increased odds of undergoing radical nephrectomy rather than partial nephrectomy (OR 4.80, 95% C.I.: 1.71–13.50). After adjusting for relevant variables, the association was attenuated but showed a trend for a statistical significance with P=0.08.
Table 4.
Predictors of diagnosis with advanced stage RCC and receiving radical nephrectomy in HAs
| Advanced Stage1 | Radical Nephrectomy2 | |||
|---|---|---|---|---|
| OR (95% C.I.) | P | OR (95% C.I.) | P | |
| Age | ||||
| <50 | Reference | 0.04 | ||
| 50–64 | 3.66 (0.82–16.31) | |||
| ≥65 | 10.48 (1.69–64.89) | |||
| Primary Language | ||||
| English | Reference | 0.01 | Reference | 0.08 |
| Spanish | 4.61 (1.38–15.40) | 4.24 (0.87–20.76) | ||
| Insurance Type | ||||
| Private | Reference | 0.08 | ||
| Public | 0.28 (0.07–1.15) | |||
| Histologic Subtype | ||||
| Clear Cell | Reference | 0.06 | ||
| Others | 9.46 (0.92–97.64) | |||
| BMI | ||||
| Normal | Reference | 0.04 | ||
| Overweight | 0.04 (0.01–0.74) | |||
| Obese | 0.03 (0.01–0.47) | |||
| Stage | ||||
| I or II | Reference | 0.02 | ||
| III or IV | 5.83 (1.34–25.25) | |||
Variables with statistically significant finding and showing suggestive association with P<0.10 are shown on the table.
Model includes age, gender, primary language, histologic subtype, insurance type, BMI, and comorbidity (diabetes and hypertension). Patients without insurance information and patients without insurance (low number) were not included.
Model includes age, gender, language, BMI, stage at diagnosis, and surgical year. Patients with metastasis at diagnosis were not included for analysis of nephrectomy type. Statistically significant findings are shown with bolded letters.
Discussion
We examined the variation in clinical and pathologic characteristics across the racial/ethnic groups and demonstrated that RCC health disparities exists among RCC patients in Arizona. We found that HAs were diagnosed with RCC at a younger age than EAs patients. ccRCC histology as well as comorbid conditions, for example diabetes, were found to be more common among HAs patients than EAs patients. These findings are in concordance with prior studies about RCC in HAs5,12. Although the analysis results should be treated with cautions due to small sample size, we also found similar characteristics in the NA patients, such as younger age of diagnosis, higher frequency of ccRCC, and higher prevalence of diabetes than EA patients. Moreover, our results suggest that race/ethnicity and obesity are risk factors independently associated with increased odds of RCC diagnosis at a younger age (<50 years).
Kidney cancer incidence rate has increased over past decades, especially in the younger age group (<50)13. The strong associations between obesity and kidney cancer incidence or mortality have been reported previously14,15. Increase in RCC incidence rate is partly due to increase in obesity, and a study estimated 5% increase in RCC incidence risk per 1 kg/m2 increase in BMI16. Racial/ethnic minority groups, including AAs, NA, and U.S. born HAs, have higher kidney cancer incidence and mortality rates1,2,17. Obesity, diabetes, and hypertension are risk factors for kidney cancer that are potentially causing disparities. Hypertension is not as prevalent in HAs and NAs as in in AAs, and HAs and NAs have slightly lower hypertension prevalence as EAs18. However, obesity is more prevalent among HAs and NAs than EAs19,20. It is possible that obesity affects RCC in HAs and NAs through different biologic mechanisms. The 2014 National Health Interview Survey results show that HAs and NAs have a higher prevalence of diabetes than EAs21. Notably a higher proportion of NAs reported having kidney disease compared to other racial/ethnic groups, and more HAs reported having kidney disease than EAs.
Issues related to access to health care or limited health care utilization may also explain the higher kidney cancer burden among racial/ethnic minority groups. We observed a higher proportion of racial/ethnic minority patients diagnosed with advanced stage RCC, and including the insurance type in the regression model did not change the association suggesting that factors other than insurance affected health care access and utilization among them. Sub-analysis for HA patients was performed to elucidate specific risk factors among them. Various factors, such as transportation, linguistic and cultural barriers, knowledge on cancer, cultural belief, and mistrust, are known to affect health care access and utilization among racial/ethnic minority groups22,23. In our patients, older HAs and HAs who spoke Spanish were more likely to have advanced RCC at presentation. These older Spanish speaking HAs may have had reduced access to health care or reduced health care utilization, which led to a diagnosis with advanced stage RCC.
Regardless of the surgical approach (laparoscopic/robotic vs. open), obese patients represent a surgical challenge. However, several studies have demonstrated the feasibility of performing nephron sparing surgery or utilization of minimally invasive techniques in obese patients without any significant adverse outcomes when compared to non-obese patients24–26. Currently, criteria to decide whether a patient is a candidate for nephron sparing surgery versus radical nephrectomy is based on tumor characteristics and not on BMI. The association between BMI and radical nephrectomy in this study probably reflects the academic setting of our institution where challenging cases are routinely referred to. Given the high proportion of obese patients as well as obese individuals in racial/ethnic groups, special attention should be given to these patients while counseling for surgical treatments.
There are several limitations of this study. First, patients are from a single academic hospital in southern Arizona, so our findings may not be generalizable. There may be patients with complicated cases of RCC (e.g., obese patients or patients with multiple comorbid conditions) referred to our hospital. Second, this is a retrospective study reviewing patients’ medical records. There was some missing information, and accuracy of information, such as race/ethnicity and family history of kidney cancer, could not be assessed. Third, samples size was very small for some racial/ethnic groups, such as NAs and AAs. Sub-analysis was also performed for a small group of Hispanic American patients. Confidence intervals were often too large, and the statistical analysis results should be treated with cautions. Finally, there was limited data available in patients’ clinical records to assess lifestyle (e.g., diet and physical exercise), health care access (e.g., geographic distance and personal finance), and environmental (e.g., exposure to environmental toxins or occupational exposures) factors associated with clinical characteristics. Multi-institutional studies including more patients and comparing lifestyle, environmental and genetic factors between the different racial groups will validate our findings and provide information to assess the causes of kidney cancer health disparities.
Conclusion
NA and HA patients have some different clinical characteristics from EA patients. NA and HA patients were diagnosed with RCC at younger age, and they are more likely to have ccRCC than EA patients. Diabetes was found to be more common among NA and HA RCC patients than EA patients. However, the causes for RCC health disparities is still not clear, and additional analysis is necessary.
Clinical Practice Points.
Renal Cell carcinoma (RCC) is the 6th most common cancer in U.S, men and the 10th most common in U.S. women. The American Cancer Society estimates that in 2018 there will be 65,340 cases (42,680 in males and 22,660 in females) of RCC with approximately 14,970 deaths. It is necessary to identify the populations at higher risk for RCC mortality and health care issues that lead to poor survival and outcomes in the high risk populations to intervene and potentially decrease the mortality. Previous studies have identified racial/ethnic minority groups, including African Americans, Hispanic Americans, and Native Americans, that had a heavier kidney cancer burden compared to European Americans.
In our study, we found that the onset varies among racial/ethnic groups. We found that Hispanic American and Native American patients were diagnosed at a younger age compared to European American patients. In logistic regression analysis, race/ethnicity and obesity were independent risk factors for diagnosis of RCC at a younger age. Similarly, our results also indicate that minority groups including Hispanic Americans and Native Americans were more likely to have comorbidity and be diagnosed with advanced renal cell carcinoma compared to European American patients.
Our findings can direct future research towards elucidating the difference in tumor behavior among the different ethnic groups and health care issues causing poor outcomes. It also brings awareness to practitioners treating patients from these racial/ethnic minority groups regarding the clinical characteristics and underlying issues in these patient populations.
Acknowledgement
The authors would like to thank everyone who helped prepare clinical data from Banner University Medical Center, particularly Myra Ortega. This project was supported by Urology Care Foundation Research Scholar Award, Institutional Research Grant number IRG-16-124-37-IRG from the American Cancer Society to University of Arizona Cancer Center, and the Partnership for Native American Cancer Prevention (NACP), funded under parallel grants, U54CA143924 (University of Arizona Cancer Center) and U54CA143925 (Northern Arizona University).
Footnotes
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Conflict of Interest
The authors do not have conflict of interest to report.
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