Ovarian epithelial dysplasia after ovulation induction: time and dose effects.

BACKGROUND Ovarian epithelial dysplasia was first described after prophylactic oophorectomies for genetic risk. Ovarian stimulation has been considered as a risk factor of ovarian cancer by Fathalla's incessant ovulation theory. In this study, we have investigated the risk of ovarian dysplasia after ovulation induction. METHODS We reviewed 99 oophorectomies or cystectomies between 1990 and 2005 divided them into two groups: previous in vitro fertilization (n = 37) and a panel of fertile controls (n = 62). Eleven epithelial cytological and architectural features were defined and an ovarian epithelial dysplasia score was calculated to quantify the degree of ovarian epithelial abnormalities. RESULTS All the ovaries were macroscopically non-cancerous except in two patients (one endometrioid cancer and one borderline tumour). The mean ovarian dysplasia score was significantly higher in the ovulation induction group than in the control group (7.64 versus 3.62, P = 0.0002). We also found a relationship between the number of ovulation-inducted cycles and the severity of ovarian dysplasia ('dose-effect') and a relationship between time after the end of ovulation induction (over 7 years) and the severity of ovarian dysplasia ('time-effect'). CONCLUSIONS There is probably a relationship between ovarian epithelial dysplasia and either ovulation inducing drugs or infertility. By Fathalla's incessant ovulation theory, 'the dose effect and the time effect' of ovarian stimulation may explain ovarian dysplasia formation.