The common analytical causes fail to explain the reason for this. The researchers reached this conclusion after a comprehensive ethnic analysis of Asian-American men of Korean, South Asian and Vietnamese origin with prostate cancer and the report is Published in the September 15, 2007 issue of CANCER, a peer-reviewed journal of the American Cancer Society.
In the U.S. in 2007, over 218,000 men are expected to be diagnosed with prostate cancer and over 27,000 will die. Established prognostic factors include age, summary stage, primary treatment, histologic grade, socioeconomic status, and year of diagnosis.
Epidemiologic studies have identified racial differences in incidence and mortality, with African-American men being at greater risk than other races. Asian-American men as a single, ethnic group have the lowest incidence of disease and the lowest mortality rate. The reasons for these racial differences remain poorly studied.
In particular, the risk among different Asian ethnicities is poorly understood, in part, because most studies have aggregated all Asians into a single racial category, ignoring the diverse ethnicities that make up Asia. The few that have tried to analyze by Asian ethnicity have typically analyzed only a few ethnicities, missing significant Asian-American ethnic populations in the process.
Interestingly, the data to date show that compared to non-Hispanic white Americans, some Asian ethnicities, such as Japanese-Americans, have higher survival rates, despite worse clinical disease, whereas others, such as Filipino-Americans, have worse survival rates. However, South Asians - e.g., Indians, Pakistanis Bangladesh, etc. - who represent the third largest Asian subgroup in America, have never been studied for prostate cancer.
Dr. Anthony Robbins of the California Cancer Registry in Sacramento, and co-investigators compared prognostic factors and survival rates of 116,916 men (108,076 whites and 8,840 Asians from the six largest represented Asian ethnicities - Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese) diagnosed with prostate cancer.
Dr. Robbins and his coauthors found that for each Asian ethnic subgroup, prognostic risk profiles were worse compared to whites. For example, all Asian ethnicities were more likely to have more advanced disease and use non-curative therapies. However, for all Asian ethnicities except South Asians, survival rates were equal to or better than whites. Japanese-Americans, for example, had significantly lower hazard ratio compared to non-Hispanic white Americans (34% lower). In contrast, South Asian-Americans had significantly higher hazard ratio compared to non-Hispanic white Americans (40% higher).
The study should help physicians more accurately apply prognostic factors to their prostate cancer patients. The authors conclude, "these results argue that traditional prognostic factors for survival from prostate cancer (stage, grade, treatment, age, year of diagnosis, and socioeconomic status), do not explain why most Asian men have better survival compared to whites, but they do explain the poorer survival of South Asian men compared to whites."