Wu A H, Whittemore A S, Kolonel L N, John E M, Gallagher R P, West D W, Hankin J, Teh C Z, Dreon D M, Paffenbarger R S
Department of Preventive Medicine, University of Southern California, Los Angeles 90033, USA.
Cancer Epidemiol Biomarkers Prev. 1995 Oct-Nov;4(7):735-41.
Differences in endogenous androgen levels have been hypothesized to explain ethnic differences in prostate cancer risk. To examine this hypothesis, we gathered data on serum concentrations of androgens and sex hormone-binding globulin (SHBG) in healthy older men from four ethnic groups at different levels of prostate cancer risk. As part of a population-based case-control study of prostate cancer we conducted in California, Hawaii, and Vancouver, Canada, 1127 African-American, white, Chinese-American, and Japanese-American control men, mostly ages 60 years or older (mean age, 69.9 years) provided information on various lifestyle factors and donated an early morning fasting blood sample between March 1990 and March 1992. We used these data to examine the distributions of serum androgens [testosterone (total, free, and bioavailable), dihydrotestosterone (DHT)], the ratio of DHT to total testosterone (DHT:testosterone ratio), and SHBG in these four ethnic groups. We also assessed correlations between concentrations of these measures with age, body size, physical activity, and other personal characteristics, and we evaluated ethnic differences in concentrations of androgens and SHBG after adjusting for these characteristics. In each of the four ethnic groups, concentrations of free and bioavailable testosterone declined with age, whereas SHBG concentrations increased with age. Age-adjusted concentrations of all androgen measures and SHBG decreased with increasing levels of Quetelet's index. After adjustment for age and Quetelet's index, androgens and SHBG showed no clear and consistent relationships to physical activity, alcohol consumption, or tobacco use. DHT:testosterone ratio was higher in men reporting a history of benign prostate disease than in men without such a history, and higher in vasectomized men than in nonvasectomized men. SHBG concentrations were higher in men reporting one or more first-degree relatives with prostate cancer than in men without such a family history. After adjustment for age and Quetelet's index, the levels of total and bioavailable testosterone were highest in Asian-Americans, intermediate in African-Americans, and lowest in whites. However, the DHT:testosterone ratio was highest in African-Americans, intermediate in whites, and lowest in Asian-Americans, corresponding to the respective incidence rates in these groups and providing indirect evidence for ethnic differences in 5alpha-reductase enzyme activity.
内源性雄激素水平的差异被认为可以解释前列腺癌风险的种族差异。为了验证这一假设，我们收集了来自四个前列腺癌风险水平不同的种族群体的健康老年男性血清雄激素和性激素结合球蛋白（SHBG）浓度的数据。作为我们在加利福尼亚、夏威夷和加拿大温哥华开展的一项基于人群的前列腺癌病例对照研究的一部分，1127名非洲裔美国、白人、华裔美国和日裔美国对照男性，大多年龄在60岁及以上（平均年龄69.9岁），提供了各种生活方式因素的信息，并在1990年3月至1992年3月期间捐献了一份清晨空腹血样。我们利用这些数据来研究这四个种族群体中血清雄激素[睾酮（总睾酮、游离睾酮和生物可利用睾酮）、双氢睾酮（DHT）]的分布、DHT与总睾酮的比值（DHT:睾酮比值）以及SHBG的分布。我们还评估了这些指标的浓度与年龄、体型、身体活动及其他个人特征之间的相关性，并在对这些特征进行调整后评估了雄激素和SHBG浓度的种族差异。在四个种族群体中的每一个群体中，游离睾酮和生物可利用睾酮的浓度都随年龄下降，而SHBG浓度随年龄增加。所有雄激素指标和SHBG的年龄调整浓度随着奎特利指数水平的升高而降低。在对年龄和奎特利指数进行调整后，雄激素和SHBG与身体活动、饮酒或吸烟之间没有明显一致的关系。报告有良性前列腺疾病病史的男性的DHT:睾酮比值高于无此类病史者，接受输精管切除术的男性高于未接受者。报告有一个或多个患前列腺癌的一级亲属的男性的SHBG浓度高于无此类家族病史者。在对年龄和奎特利指数进行调整后，总睾酮和生物可利用睾酮水平在亚裔美国人中最高，在非洲裔美国人中居中，在白人中最低。然而，DHT:睾酮比值在非洲裔美国人中最高，在白人中居中，在亚裔美国人中最低，这与这些群体各自的发病率相对应，并为5α-还原酶活性的种族差异提供了间接证据。
