Abstract
Objectives: To understand the increasing trend of racial disparity of prostate cancer in the last three decades and to evaluate the potential impact of social‐economic status, early diagnosis, cancer cell differentiation and marital status.
Method: Both prostate cancer incidence and mortality rates as well as case marital status in SEER 9 registration sites were estimated for the period 1973–2006. To stabilize estimation and adjust for social‐economic status, we collapsed SEER sites and states, and merged the 200 counties into 20 county groups based on similarity in poverty rates (percentage of population below poverty line).
Results: [1]. The incidence of prostate cancer from 1973 to 2006 increased 74% and 87% for blacks and whites, respectively. During the same time, the mortality rate declined 5% and 25% for blacks and whites, respectively. [2] The incidence rate ratio of black/whites is relatively stable, ranging from 1.4–1.8, but the mortality rate ratio of black/white increased 27%, from 1.85 to 2.34. Regression showed the R2 for the increasing trend of this ratio is 0.91. [3] When we compare the ratio of mortality over incidence, they were 0.40 and 0.35 for blacks and whites in 1973, and declined to 0.22 and 0.14 in 2006, respectively, indicating the survival rate increased for both, but the magnitude of improvement is much larger in whites than in blacks. [4] When we stratified the counties to 20 county groups, we found that there is no trend for incidence or mortality rates associated with the poverty rate increases. [5] There is also no trend of early diagnosis associated with poverty increases in whites or blacks for ages less than 65 or more than 65. Neither regression has R2 larger than 0.06. [6] Among the 20 county groups, only two showed the percent of early diagnosis in blacks lower than in whites with p<0.05. [7] Among the 20 county groups, four showed that a larger percentage of poor differentiated prostate cancer in blacks than in whites, the differences are statistically significant at =0.05 level. [8] The percent of white married cases are 77% and 72% for ages 30–64 and 65 or over, respectively, but the percentage in black counterparts are only 58% and 55%.
Conclusion: The results indicated that [1] The racial mortality disparity increased at 2% per year during 1973 to 2006. This is due to the larger decline of mortality in whites than in blacks. [2] This study does not support the relationship of disparity with social‐economic status, early diagnosis or poor differentiation of cancer cells. [3] The percent of married white cases are 33% and 30% higher than that of black counterparts for ages 30–64 years old and 65 and over, respectively. Because married cases showed better survival rates as reported by previous research, the racial disparity may be partly explained by the remarkable difference in married status of prostate cancer cases.
Citation Information: Cancer Prev Res 2010;3(1 Suppl):A94.
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