Objective: To determine the prevalence of ovarian endometriosis in malignant epithelial ovarian tumours.
Study design: A retrospective analysis of 160 malignant and 23 borderline ovarian tumours during the period 1995-2001.
Results: Fourteen (7.7%) of the tumours contained endometriosis. This affected 22% of the endometrioid and 10.8% of the mixed adenocarcinomas. The mean age of the ovarian endometriosis patients was 43+/-13 range 26-70 years. The incidence in borderline tumours 13% (3/23) was higher than that in ovarian cancer 6.9% (11/160) (P>0.05). Eight (57%) of cases were classified as atypical and six (43%) as typical endometriosis. Nine cases were FIGO (International Federation of Gynaecology and Obstetrics) stage I and 5 stage III.
Conclusions: Both malignant and borderline ovarian tumours are associated with ovarian endometriosis. In addition, atypical endometriosis was found associated with endometrioid and mixed epithelial ovarian tumours.