Effect of radiotherapy for rectal cancer on ovarian androgen production.

Abstract

The impact of radiotherapy (RT) for rectal cancer on ovarian androgen production is unknown. The aim was to examine the effect of RT for rectal cancer on androgen levels in non-oophorectomised women and the association with female sexual desire. This prospective cohort study included women treated with surgery for rectal cancer with or without RT. Serum testosterone (T), free T, androstenedione and dehydroepiandrosterone sulfate (DHEA-S) were assessed at baseline, after RT and one year postoperatively. Sexual desire was assessed with the Female Sexual Function Index. Twenty-seven participants had surgery alone (RT-) and 98 had preoperative RT and surgery (RT+). During the first year after surgery, median T and free T decreased from 0.6 (range 0.1–3.6) to 0.5 (0.1–2.3) nmol/L (p<0.001) and 9.1 (range 1.6–45.8) to 7.9 (1.4–22.7) pmol/L (p<0.001) respectively in the RT+ group and did not change in the RT- group. Longitudinal regression analysis confirmed a decrease in T and free T after RT. The adjusted change in androstenedione and DHEA-S was not significant in any group. The mean change in T (OR 2.74 (95% CI 1.06–7.11, p=0.038), free T (OR 1.08 (95% CI 1.02–1.15), p=0.011) and androstenedione (OR 1.52 (95% CI 1.07–2.16), p=0.019 was related to change in sexual desire. Radiotherapy decreases androgens predominantly derived from the ovaries, while androgens of mainly adrenal origin remain unchanged. Reduction in ovarian derived androgens maybe associated with reduced sexual desire.