Socioeconomic status and prostate cancer incidence and mortality across racial/ethnic groups in California

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BACKGROUND: The racial/ethnic difference in prostate cancer rates is well documented, with the highest incidence and mortality rates observed among African-Americans followed by non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders. Whether socioeconomic status (SES) can account for these differences in risk has been investigated in previous studies, but with conflicting results. Moreover, previous studies have focused primarily on the differences between African-Americans and non-Hispanic Whites and little is known for Hispanics and Asian/Pacific Islanders. To further investigate the relationship between SES and prostate cancer among these four groups, we examined 97,172 incident prostate cancer cases (diagnosed in 1998-2002) and 6,432 prostate cancer deaths (1999-2001) from the diverse population of California. METHODS: Data were abstracted from the California Cancer Registry, a population-based SEER (Surveillance, Epidemiology, and End Results) registry. Each prostate cancer case and death was assigned a previously validated, multidimensional neighborhood-SES index using the 1990 and 2000 U.S. Census data. SES quintile-specific prostate cancer incidence and mortality rates and rate ratios were estimated using SEER*Stat for each race/ethnicity categorized into 10-year age groups. RESULTS: For prostate cancer incidence, across all SES levels and age groups except for older men aged 75-84 years, African-Americans had the highest rates followed by non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders. Among older men, the racial/ethnic-specific pattern was similar except for a higher incidence of prostate cancer among Hispanics than non-Hispanic Whites for SES quintiles 2 through 5. Similar racial/ethnic-specific patterns in incidence were seen for aggressive prostate cancer (regional/distant tumors or localized tumors that were either poorly differentiated or undifferentiated). For prostate cancer mortality, across all SES levels and age groups, the highest rates were seen among African-Americans, followed by non-Hispanic Whites, Hispanics, and Asian/Pacific Islanders. The largest significant differences in mortality rates were seen among men 45-54 years of age, whereby African Americans had 4-5-fold higher rates than non-Hispanic Whites for SES quintiles 2 (P = 0.004) and 3 (P = 0.001). CONCLUSIONS: Our findings suggest that socioeconomic status cannot account for the racial/ethnic differences in prostate cancer incidence and mortality, pointing towards biological and environmental factors playing an important role in the disparity across racial/ethnic groups.