Androgen receptor gene CAG and GGN repeat lengths as predictors of recovery of spermatogenesis following testicular germ cell cancer treatment

Spermatogenesis is an androgen-regulated process that depends on the action of androgen receptor (AR). Sperm production may be affected in men treated for testicular cancer (TC), and it is important to identify the factors influencing the timing of spermatogenesis recovery following cancer treatment. It is known that the CAG and GGN repeat numbers affect the activity of the AR; therefore, the aim of this study is to investigate if the CAG and GGN polymorphisms in the AR gene predict recovery of sperm production after TC treatment. TC patients (n = 130) delivered ejaculates at the following time points: postorchiectomy and at 6, 12, 24, 36, and 60 months posttherapy (T0, T6, T12, T24, T36, and T60). The CAG lengths were categorized into three groups, <22 CAG, 22-23 CAG, and >23 CAG, and the GGN tracts were also categorized into three groups, <23 GGN, 23 GGN, and >23 GGN. At T12, men with 22-23 CAG presented with a statistically significantly (P = 0.045) lower sperm concentration than those with other CAG numbers (8.4 × 10 6 ml-1 vs 16 × 10 6 ml-1 ; 95% CI: 1.01-2.65). This association was robust to omitting adjustment for treatment type and sperm concentration at T0 (P = 0.021; 3.7 × 10 6 ml-1 vs 10 × 10 6 ml-1 ; 95% CI: 1.13-4.90). The same trends were observed for total sperm number. The least active AR variant seems to be associated with a more rapid recovery of spermatogenesis. This finding adds to our understanding of the biology of postcancer therapy recovery of fertility in males and has clinical implications.