Date Published: May 23, 2018
Publisher: Public Library of Science
Author(s): Mindy C. DeRouen, Lauren Hu, Meg McKinley, Kathleen Gali, Manali Patel, Christina Clarke, Heather Wakelee, Robert Haile, Scarlett Lin Gomez, Iona Cheng, Hajo Zeeb.
The relationships between neighborhood factors (i.e., neighborhood socioeconomic status (nSES) and ethnic enclave) and histologic subtypes of lung cancer for racial/ethnic groups, particularly Hispanics and Asian American/Pacific Islanders (AAPIs), are poorly understood.
We conducted a population-based study of 75,631 Californians diagnosed with lung cancer from 2008 through2012. We report incidence rate ratios (IRRs) for lung cancer histologic cell-types by nSES among racial/ethnic groups (non-Hispanic (NH) Whites, NH Blacks, Hispanics and AAPIs) and according to Hispanic or Asian neighborhood ethnic enclave status among Hispanics and AAPIs, respectively. In addition, we examined incidence jointly by nSES and ethnic enclave.
Patterns of lung cancer incidence by nSES and ethnic enclave differed across race/ethnicity, sex, and histologic cell-type. For adenocarcinoma, Hispanic males and females, residing in both low nSES and high nSES neighborhoods that were low enclave, had higher incidence rates compared to those residing in low nSES, high enclave neighborhoods; males (IRR, 1.17 [95% CI, 1.04–1.32] and IRR, 1.15 [95% CI, 1.02–1.29], respectively) and females (IRR, 1.29 [95% CI, 1.15–1.44] and IRR, 1.51 [95% CI, 1.36–1.67], respectively). However, AAPI males residing in both low and high SES neighborhoods that were also low enclave had lower adenocarcinoma incidence.
Neighborhood factors differentially influence the incidence of lung cancer histologic cell-types with heterogeneity in these associations by race/ethnicity and sex. For Hispanic males and females and AAPI males, neighborhood ethnic enclave status is strongly associated with lung adenocarcinoma incidence.
Lung cancer is the second-most common cancer among both males and females in the U.S. with over 222,500 new cases of lung cancer estimated to be diagnosed in 2017 . Lower area-level socioeconomic status (SES) has been associated with a higher incidence of overall lung cancer and non-small-cell lung cancer (NSCLC) among non-Hispanic White and non-Hispanic Black males and females and Asian American/Pacific Islander (AAPI) males [2–5]. Disparities in the burden of lung cancer according to area-level SES may be mediated by higher smoking prevalence, lower access to and use of health care services, and/or greater exposure to environmental contaminants such as air pollution, radon, or asbestos among those residing in lower SES neighborhoods [6–10]. On the other hand, lower area-level SES has been associated with lower incidence of overall lung cancer and NSCLC among Hispanic males and females [2, 4, 5]. The reason for this paradoxical association among Hispanics is unknown, but the ethnic composition of neighborhoods, rather than SES, has been suggested to play a key role . Finally, while incidence of overall lung cancer and NSCLC according to area-level SES has been examined among AAPI females, no patterns have been reported [2, 4, 5] and other neighborhood factors such as Asian enclave have not yet been examined among AAPIs.
The distribution of neighborhood factors and clinical characteristics among the 75,631 lung cancer cases diagnosed from 2008–2012 are presented in Table 1. Approximately, 67% of Hispanics and 71% of Blacks resided in lower SES neighborhoods (first and second quartiles) in comparison to 41.9% of AAPIs and 42.3% of Whites. Proportionally more Hispanics and AAPIs resided in the highest enclave neighborhoods. Across all racial/ethnic groups combined, adenocarcinoma (47.5%) was the most common histologic cell-type.
In this population-based study with over 75,000 lung cancer cases, we observed higher incidence of lung cancer among Black and White males and females and AAPI males residing in lower SES neighborhoods. In contrast, incidence did not differ by nSES among AAPI females and Hispanic males, while an inverse association was observed among Hispanic females such that lung cancer incidence was actually lower in lower SES neighborhoods. However, examining histologic cell-type-specific lung cancer incidence according to nSES indicated somewhat varying patterns, especially among Hispanics and AAPIs. Among Hispanics and AAPIs, we also observed varying patterns of lung cancer incidence according to ethnic enclave that were specific to groups defined by sex, race/ethnicity, and histologic cell type. Examining incidence patterns jointly by nSES and ethnic enclave among Hispanics and AAPIs suggested that nSES-related gradients may, in some cases, be driven more by ethnic enclave status rather than by SES.
Our study illustrates varying patterns of incidence of lung cancer histologic cell types according to neighborhood SES and ethnic enclave by sex and race/ethnicity. It is important for continuing research on lung cancer etiology to consider, in addition to individual-level exposures (e.g.; smoking status, individual-level SES), the clear contextual-level effects of nSES and, for Hispanics and AAPIs, the joint effects of nSES and ethnic enclave.