Hanisch LJ, Bryan CJ, James JL, Pisansky TM, Corbett TB, Parliament MB, Stewart CE, Hartford AC, Sandler H, Berk LB, Kachnic L, Bruner DW. Impact of sildenafil on marital and sexual adjustment in patients and their wives after radiotherapy and short-term androgen suppression for prostate cancer: analysis of RTOG 0215. Support Care Cancer. 2012 Nov; 20(11):2845-50.