Zeegers Maurice P, Kiemeney Lambertus A L M, Nieder Alan M, Ostrer Harry
Department of Public Health and Epidemiology, School of Medicine, Public Health Building, University of Birmingham, Birmingham B15 2TT, United Kingdom.
Cancer Epidemiol Biomarkers Prev. 2004 Nov;13(11 Pt 1):1765-71.
Although narrative reviews have suggested an association between (CAG)n and (GGN)n polymorphisms in the AR gene and prostate cancer, it has never been quantified systematically. The purpose of this meta-analysis was to provide relative and absolute quantitative summary estimates with sufficient power.
Publications were identified through database searches for epidemiologic studies published until February 2004. For each study, mean differences in repeat length between cases and controls were calculated as well as continuous odds ratios (OR) per one CAG or GGN repeat decrement and discrete ORs to compare prostate cancer risk in men with short CAG repeats (</=21 repeats) versus long CAG repeats (>21 repeats) and short GGN repeats (</=16 repeats) versus long GGN repeats (>16 repeats). The study-specific estimates were combined by random effects metaregression analyses.
Nineteen case-control studies were included in this review comprising a total of 4,274 cases and 5,275 controls. Prostate cancer cases had on average 0.26 fewer CAG repeats and 0.09 fewer GGN repeats than controls. The continuous ORs of prostate cancer per one repeat decrement were 1.02 and 1.01 for CAG and GGN repeats, respectively. The summary discrete OR (95% confidence interval) were 1.19 (1.07-1.31) and 1.31 (1.06-1.61) for CAG and GGN repeat polymorphisms, respectively.
Although the presence of shorter repeats seemed to be modestly associated with prostate cancer risk, the absolute difference in number of repeats between cases and controls is <1 repeat. We question whether such a small difference is enough to yield measurable biological impact in prostate carcinogenesis.
尽管叙述性综述表明雄激素受体（AR）基因中的（CAG）n和（GGN）n多态性与前列腺癌之间存在关联，但从未进行过系统量化。本荟萃分析的目的是提供具有足够效力的相对和绝对定量汇总估计值。
通过检索数据库识别截至2004年2月发表的流行病学研究。对于每项研究，计算病例组和对照组之间重复长度的平均差异，以及每减少一个CAG或GGN重复的连续比值比（OR），并计算离散OR，以比较CAG重复短（≤21次重复）与CAG重复长（>21次重复）的男性以及GGN重复短（≤16次重复）与GGN重复长（>16次重复）的男性患前列腺癌风险。通过随机效应荟萃回归分析合并各研究的估计值。
本综述纳入了19项病例对照研究，共4274例病例和5275例对照。前列腺癌病例的CAG重复平均比对照组少0.26个，GGN重复平均比对照组少0.09个。CAG和GGN重复每减少一个重复，前列腺癌的连续OR分别为1.02和1.01。CAG和GGN重复多态性的汇总离散OR（95%置信区间）分别为1.19（1.07 - 1.31）和1.31（1.06 - 1.61）。
尽管较短重复的存在似乎与前列腺癌风险有适度关联，但病例组和对照组之间重复数的绝对差异<1个重复。我们质疑如此小的差异是否足以在前列腺癌发生过程中产生可测量的生物学影响。
