Shorter GGN Repeats in Androgen Receptor Gene Would Not Increase the Risk of Prostate Cancer

Abstract

The association between the polymorphic GGN repeat in androgen receptor gene and prostate cancer susceptibility has been studied extensively. But the results of these polymorphisms with prostate cancer risk remain inconclusive. Previous meta-analysis showed short GGN repeats (≤16 repeats) had high risks for prostate cancer compared with longer GGN repeats (>16 repeats). Many studies have been published since the release of the previous meta-analysis. Here, we conducted an updated meta-analysis to demonstrate whether short repeats have higher risks for prostate cancer compared to long repeats. Five databases (PubMed, EMBASE, Cochrane Library, The China National Knowledge Infrastructure, and Web of Science) were last searched until January 1, 2016. Random- or fixed-effects model was performed based on the heterogeneity among studies. The potential publication bias was assessed via Begg funnel plot and Egger regression test. Twelve out of 157 studies were extracted. The result indicated that there was no significant difference between short repeat group and long repeat group in the overall analysis ( I² = 80.6%, P = .000, odds ratio = 1.31, 95% confidence interval: 0.93-1.83). There was no association between the length of GGN repeats and the occurrence of prostate cancer in both Caucasian and African American ( I² = 6.7%, P = .359, odds ratio = 1.11, 95% confidence interval: 0.94-1.32; and I² = 74.1%, P = .050, odds ratio = 0.963, 95% confidence interval: 0.36-2.58). Our result demonstrated that a shorter GGN repeat polymorphism cannot increase the risk of prostate cancer compared to the longer GGN repeats. That's different with previous meta-analysis.

Keywords: GGN repeats; androgen receptor; gene; meta-analysis; prostate cancer.

Figure 1.

Flowchart showing the selection process for the included studies.

Figure 2.

Forest plot of odd ratios (ORs) of all studies using a random-effects model.

Figure 3.

Forest plot of odd ratios (ORs) of Caucasian by ethnicity using a fixed-effects model.

Figure 4.

Forest plot of odd ratios (ORs) of African American by ethnicity using a random-effects model.

Figure 5.

A, Begg funnel plot for publication bias test of overall analysis. B, Begg funnel plot for publication bias test of Caucasian by subgroup. C, Begg funnel plot for publication bias test of African American by subgroup.