Table 2.
Associations Between Second Primary Lung Cancer and Participant Characteristics in the Multiethnic Cohort.
| Characteristic | Hazard Ratio (95% CI) | P |
|---|---|---|
| Primary Analyses | ||
| Smoking status | ||
| Never | Reference | |
| Former | 1.32 (0.79–2.20) | 0.284 |
| Current | 1.80 (1.07–3.03) | 0.028 |
| Smoking per 10 pack-years | 1.18 (1.09–1.27) | <0.001 |
| Smoking per 10 cigarettes per day | 1.30 (1.12–1.51) | <0.001 |
| Smoking per 1 quit yeara | 0.97 (0.95–0.99) | 0.010 |
| Met the USPSTF criteria | ||
| No | Reference | |
| Yes | 1.92 (1.39–2.64) | <0.001 |
| BMI (per 1 kg/m2) | 1.02 (0.99–1.05) | 0.267 |
| Personal history of cancer | ||
| No | Reference | |
| Yes | 1.30 (0.93–1.82) | 0.120 |
| Family history of lung cancer | ||
| No | Reference | |
| Yes | 0.82 (0.47–1.42) | 0.472 |
| Secondary Analyses | ||
| Sex | ||
| Female | Reference | |
| Male | 1.24 (0.91–1.70) | 0.179 |
| Race/ethnicity | ||
| White | Reference | |
| African American | 1.00 (0.65–1.55) | 0.989 |
| Japanese American | 0.80 (0.52–1.24) | 0.324 |
| Latino | 0.89 (0.53–1.51) | 0.679 |
| Native Hawaiian | 1.09 (0.60–2.00) | 0.769 |
| Other | 0.71 (0.33–1.50) | 0.370 |
| Education | ||
| High school or less | Reference | |
| Some college or graduate | 1.12 (0.81–1.55) | 0.501 |
| Postgraduate | 0.93 (0.53–1.63) | 0.799 |
| IPLC surgery | ||
| No | Reference | |
| Yes | 1.89 (1.16–3.07) | 0.010 |
| IPLC radiotherapy | ||
| No | Reference | |
| Yes | 0.64 (0.41–0.98) | 0.041 |
| IPLC chemotherapy | ||
| No | Reference | |
| Yes | 0.55 (0.35–0.88) | 0.013 |
| Covariates | ||
| Age at IPLC diagnosis (per 1 year) | 1.00 (0.98–1.02) | 0.841 |
| IPLC stage | ||
| Local/regional | Reference | |
| Distant | 0.33 (0.20–0.56) | <0.001 |
| Expanded IPLC stage | ||
| Local | Reference | |
| Regional | 0.68 (0.48–0.96) | 0.028 |
| Distant | 0.28 (0.16–0.47) | <0.001 |
| IPLC histology | ||
| Squamous cell carcinoma | Reference | |
| Adenocarcinoma | 1.11 (0.76–1.64) | 0.584 |
| Large cell carcinoma | 1.66 (0.80–3.46) | 0.173 |
| Small cell carcinoma | 0.43 (0.13–1.40) | 0.162 |
| Other | 0.65 (0.38–1.13) | 0.130 |
All cause-specific proportional hazards models accounted for the competing risk of death. Variables in the primary and secondary analyses were evaluated in individual cause-specific proportional hazards regression models adjusting for age at IPLC diagnosis, IPLC histology, and IPLC stage. Among covariates, age at IPLC diagnosis was adjusted for IPLC histology and stage, IPLC histology was adjusted for IPLC age and stage, and IPLC stage was adjusted for IPLC age and histology.
Abbreviations: CI confidence interval, USPSTF United States Preventive Services Task Force, BMI body mass index, kg kilogram, m meter, IPLC initial primary lung cancer.
Smoking quit years were assessed only among ever smokers (N=6,196).