Long-term follow-up of a racially and ethnically diverse population of men with localized prostate cancer who did not undergo initial active treatment.

Background: There is limited research on the racial/ethnic differences in long-term outcomes for men with untreated, localized prostate cancer.

Methods: Men diagnosed with localized, Gleason ≤7 prostate cancer who were not treated within 1 year of diagnosis from 1997-2007 were identified. Cumulative incidence rates of the following events were calculated; treatment initiation, metastasis, death due to prostate cancer and all-cause mortality, accounting for competing risks. The Cox model of all-cause mortality and Fine-Gray sub distribution model to account for competing risks were used to test for racial/ethnic differences in outcomes adjusted for clinical factors.

Results: There were 3925 men in the study, 749 Hispanic, 2415 non-Hispanic white, 559 non-Hispanic African American, and 202 non-Hispanic Asian/Pacific Islander (API). Median follow-up was 9.3 years. At 19 years, overall cumulative incidence of treatment, metastasis, death due to prostate cancer, and all-cause mortality was 25.0%, 14.7%, 11.7%, and 67.8%, respectively. In adjusted models compared to non-Hispanic whites, African Americans had higher rates of treatment (HR = 1.39, 95% CI = 1.15-1.68); they had an increased risk of metastasis beyond 10 years after diagnosis (HR = 4.70, 95% CI = 2.30-9.61); API and Hispanic had lower rates of all-cause mortality (HR = 0.66, 95% CI = 0.52-0.84, and HR = 0.72, 95% CI = 0.62-0.85, respectively), and API had lower rates of prostate cancer mortality in the first 10 years after diagnosis (HR = 0.29, 95% CI = 0.09-0.90) and elevated risks beyond 10 years (HR = 5.41, 95% CI = 1.39-21.11).

Conclusions: Significant risks of metastasis and prostate cancer mortality exist in untreated men beyond 10 years after diagnosis, but are not equally distributed among racial/ethnic groups.