Introduction and Objective: Latinos constitute a significantly heterogeneous population with unique national identities, sociodemographic characteristics, and ancestry. The prostate cancer (PC) incidence patterns and clinical characteristics are poorly characterized among U.S. Latinos. This gap of knowledge hinders adequate risk-stratification strategies. Particularly lacking are studies that consider Latino subpopulations defined by country of origin. We investigated sociodemographic and clinical characteristics and outcomes of 321,433 men diagnosed with PC in California from 1988-2012, accounting for ethnicity and country of origin using data from the California Cancer Registry.

Materials and Methods: Latino status and country of origin were identified by the NAACCR Hispanic Identification. We grouped Latinos (15.9% of all cases) into the following origins: Mexico (MEX, 26.3%), Central/South America (CSA, 6.9%), Cuba (1.3%), Puerto Rico (PR, 0.8%), and unspecified (64.6%). Non-Latino white (NLW, 73.4%) and non-Latino Blacks (NLB, 10.4%) were used for comparison. Nativity (U.S.-born versus foreign-born Latinos) was defined based on birthplace information available in the cancer registry records. SES was based on the geocoding of the participants' residential address at diagnosis at the census block group level, using a well-established methodology. Annual age-adjusted incidence rates (AAIRs) were calculated. Pearson's Chi-square was used to test differences among ethnicities and subgroups. Logistic regression was used to test the relationship between changes in Gleason score from biopsy to surgery among all ethnicities and subgroups.

Results: Among known LAT subpopulations, Mexicans had the lowest AAIR (44 per 100,000) and Central/South American LAT had the highest (90 per 100,000), followed by Cubans (85 per 100,000) and Puerto Ricans (52 per 100,000). Latinos had a slightly higher proportion of younger diagnoses than NLW, with central/south Americans having the greatest proportion. LAT were more likely to have lower SES than NLW, and more likely to be uninsured. NLB were more likely to have elevated PSA (94.2%) vs NLW (89.0%) and LAT (91.8%, p<0.001). Latinos had the highest proportion of nonlocalized PC relative to NLW and NLB (18.3% vs 15.6% vs 18.1%, p<0.001), among them MEX having the highest proportion (22.5%). MEX also had the longest time from diagnosis to treatment relative to other Latino subgroups. Among all men, surgery and radiation were the most-used treatments followed by no treatment. Cubans had the lowest receipt of treatment. Fewer Latinos reported receiving radiation therapy (28.5%) than NLB or NLW (31.8% and 32.2%, p<0.001), and among them PR had the highest proportion of radiation treatment whereas CSA had a greater proportion of surgery. Latinos had a greater proportion of cases with no treatment reported (15.3%) vs NLW and NLB. There were no differences among NLB, NLW, and Latinos for Gleason change from biopsy to surgery among surgical patients. Logistic regression analysis showed that among all ethnicities and subgroups, time from diagnosis to treatment had a protective effect on the risk of Gleason score change from biopsy to surgery. Among all Latinos by nativity status, foreign born were older, mainly came from MEX, of low SES, and were uninsured. Foreign-born Latinos had a higher percentage of nonlocalized PC, more cores positive for PC on biopsy, and had more cases treated with radiation.

Conclusion: We observed differences in PC incidence patterns and patient and clinical characteristics among Latino men in California. This highlights the importance of considering the heterogeneity in this minority population in understanding the cancer determinants and patterns of care for PC among Latinos.

Citation Format: Alexis R. Freedland, Andre E. Kim, Juanjuan Zhang, Ann Hamilton, Dennis Deapen, Lihua Liu, Inderbir S. Gill, Mariana C. Stern. Disparities in prostate cancer incidence, patient and clinical characteristics among Latino subpopulations defined by country of origin in California: Findings from the California Cancer Registry [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A82.