Abstract C30: Mortality Differences in Younger and Older Breast Cancer Patients according to Insurance, Race/Ethnicity, and Neighborhood Socioeconomic Status in the California Cancer Registry
Authors: Tao Li , Gomez Scarlett Lin , Thompson Caroline , Tsou Ming-Hsiang , Gibbons Joseph , Nodora Jesse N. , Komenaka Ian , Schwab Richard , Unkart Jonathan , Murphy James , Martinez Maria Elena 
Published: March 2017

Introduction: In the U.S., approximately 25% of all breast cancer cases occur before the age of 50 years. Younger age at diagnosis of breast cancer is associated with lower survival when compared to older cases. Data on sociodemographic predictors of mortality in younger vs. older breast cancer patients are scarce. We assessed differences in risk of total mortality between women 50 years and younger vs. those &gt;50 years, according to health insurance status, race/ethnicity, and neighborhood socioeconomic status (nSES).

Methods: We used data from the population-based California Cancer Registry including invasive female breast cancer cases 18 years of age and older diagnosed between 2005 and 2012 with follow-up through December 31, 2013 and identified 145,564 women. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for total mortality for younger (≤years) and older (&gt;50 years) patients. Multivariable models were stratified by stage, allowing baseline hazards to vary by stage, and adjusted for year of diagnosis, single year age, race/ethnicity, nSES, insurance status, tumor subtype, grade, histology, tumor size, lymph node status, as well as treatment modalities (surgery, chemotherapy, and radiation therapy).

Results: Among 145,564 breast cancer cases, 3971 total deaths occurred in patients ≤50 years of age and 18,639 deaths in those &gt;50 years. Significant interactions by age group were observed for race/ethnicity (&lt;0.0001), nSES (p&lt;0.0006), and health insurance (p&lt;0.0001). HRs comparing mortality among black versus NHW women were greater for younger women (HR=1.33; 95% CI=1.20-1.49) than for older women (HR=1.12; 95% CI=1.06-1.19). Among older patients, lower HRs were observed for Hispanic (HR=0.87; 95% CI, 0.83-0.91) and Asian/Pacific Islander (API) women (HR=0.73; 95% CI, 0.69-0.77) compared to NHW patients, but no difference was observed among younger patients. In younger women, compared to patients with private health insurance, HRs were higher for women with public (HR=1.52; 95% CI=1.39-1.66) or no insurance (HR=1.24; 95% CI=1.14-1.35). Corresponding HRs for insurance status were lower among older patients.

Conclusions: Our results show differences in total mortality associated with important sociodemographic factors comparing younger to older breast cancer patients. Specifically, higher risks of dying were observed for non-privately vs. privately insured patients and for Blacks vs. NHWs in younger compared to older women, even after accounting for clinical and other sociodemographic factors. These results suggest that access to care is possibly a more important driver in mortality outcome in younger vs. older women, and additional analyses will evaluate the extent to which treatment explains these differences. The findings are important given the higher rates of recurrence and less favorable survival in younger compared to older breast cancer patients.

Citation Format: Li Tao, Scarlett Lin Gomez, Caroline Thompson, Ming-Hsiang Tsou, Joseph Gibbons, Jesse N. Nodora, Ian Komenaka, Richard Schwab, Jonathan Unkart, James Murphy, Maria Elena Martinez. Mortality Differences in Younger and Older Breast Cancer Patients according to Insurance, Race/Ethnicity, and Neighborhood Socioeconomic Status in the California Cancer Registry. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C30.