Interracial comparative study of prostate cancer in the United States, China, and Japan

The interracial differences of prostate cancer progression have long been documented; however, underlying molecular and cellular mechanisms remain obscure. This study focuses on the histopathologic, immunohistochemical, biochemical, and molecular characterization of prostate cancer tissues unselectively obtained from US, Chinese, and Japanese men. Histopathologic analyses indicate that 74.5% of the prostate cancers in Chinese patients were poorly differentiated, compared with 28.6 and 32.8% of the prostate cancers in US and Japanese men, respectively. These differences cannot be attributed to patient age, clinical stage of disease, or methods of tissue sampling. Furthermore, the high proportion of poorly differentiated prostate cancer tissues in the Chinese group was not related to the patients' access to medical service or their geographic origins within China. We found significantly higher levels of tumor angiogenesis (2- to 4-fold), serotonin (2- to 20-fold), and bombesin (7- to 16-fold), but not chromogranin A, in tissue specimens obtained from Chinese prostate cancer patients compared with those from US and Japanese patients. We also found marked differences in p53 protein accumulation among various ethnic groups. The p53 protein was frequently detected in prostate cancer tissue specimens from Chinese (90.2%), but less frequently in US black (3.7%), US white (17.4%), and Japanese (7.1%) men. Further analysis of 31 prostate cancer tissues from Chinese men indicated that mutational changes in the p53 gene occurred between exons 5 and 8.