Abstract A086: Racial and ethnic disparities in prostate cancer survival in the Multiethnic Cohort Study (MEC)
Authors: Xiong Wei , Chen Fei , Hamilton Ann S. , Conti David , Hughley Raymond , Bogumil David , Wang Anqi , Park Song-Yi , Wan Peggy , Wilkens Lynne R. , Le Marchand Loïc , Hernandez Brenda Y. , Haiman Christopher A. 
Published: September 2024

Abstract
Background: Prostate cancer (PCa) survival has improved over the past 20 years due to advancements in treatment and screening. However, racial and ethnic disparities in PCa survival remain. Studying population differences in PCa survival may help identify underlying contributing factors. Methods: We conducted survival analyses among 10,651 African American, Latino, Native Hawaiian, Japanese American, and non-Hispanic White (NHW) men with an incident PCa diagnosis since 1993 who were part of the Multiethnic Cohort Study. Sub- hazard ratios (SHRs) and 95% confidence intervals (CI) were estimated using the Fine and Grey Subdistribution Hazards Model to account for competing risks in PCa-specific mortality, with age since diagnosis as the time metric. Multivariable models included age at PCa diagnosis, Gleason score, stage at diagnosis, and baseline values of education, initial treatment (radiation, surgery, hormone therapy, chemotherapy, or no active treatment), diabetes history, physical activity, BMI, smoking status, and dietary intakes linked to PCa progression (tomatoes, whole milk, fatty fish, processed meat, saturated fat, and alcohol). We also performed stratified analyses by tumor stage (localized or regional/distant) and Gleason score (≤7 or &gt;7). Associations were considered statistically significant at P &lt; 0.05. Results: Of 10,651 men diagnosed with PCa over 27 years of follow-up (mean duration, 8.4 years), 1,324 (12.4%) died of PCa. Those with lower Gleason scores were less likely to die than those with higher scores (6.8% of men with Gleason score ≤7 vs 21.3% of men with Gleason score &gt;7, p&lt;0.001). Likewise, men with localized disease were less likely to die than men with regional/distant disease (7.5% of men with localized disease vs. 29.2% of men with regional/distant disease, p&lt;0.001). Japanese Americans had significantly lower mortality compared with NHWs (SHR=0.63, 95% CI:0.51, 0.79, p&lt;0.001), consistently observed across stage and Gleason score: localized (SHR=0.64, 95% CI: 0.48, 0.87, p&lt;0.001); regional/distant (SHR=0.63, 95% CI: 0.45, 0.88, p=0.01); Gleason ≤7 (SHR=0.61, 95% CI: 0.44, 0.86, p&lt;0.001); and Gleason score &gt;7 (SHR=0.59, 95% CI: 0.43, 0.79, p&lt;0.001). PCa-specific mortality was significantly higher among African Americans compared to NHWs (SHR=1.31, 95% CI: 1.08-1.60, p=0.01). This difference was more pronounced for less aggressive tumors: localized (SHR=1.50, 95% CI: 1.15, 1.96, p&lt;0.001); Gleason ≤7 (SHR=1.28, 95% CI: 0.95, 1.71, p=0.11). Lastly, we did not observe significant differences in PCa mortality for Latinos and Native Hawaiians compared to NHWs overall or by disease severity. Conclusions: Japanese American have ∼40% lower and African Americans have ∼30% higher PCa-specific mortality relative to NHWs, even after accounting for lifestyle/behavioral factors, stage, Gleason score, and treatment. Further investigations are needed to explore social and cultural factors that impact care as well as tumor-based characteristics that may vary between populations to understand these disparities in PCa mortality.
Citation Format: Wei Xiong, Fei Chen, Ann S. Hamilton, David Conti, Raymond Hughley, David Bogumil, Anqi Wang, Song-Yi Park, Peggy Wan, Lynne R. Wilkens, Loïc Le Marchand, Brenda Y. Hernandez, Christopher A. Haiman. Racial and ethnic disparities in prostate cancer survival in the Multiethnic Cohort Study (MEC) [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A086.