Endometrium is not the primary site of origin of pelvic high-grade serous carcinoma in BRCA1 or BRCA2 mutation carriers.

Serous endometrial intraepithelial carcinoma has been proposed to be a potential precursor lesion of pelvic high-grade serous carcinoma. If true, an increased incidence of uterine papillary serous carcinomas would be expected in BRCA1 and BRCA2 mutation carriers, who are at high-risk of developing pelvic high-grade serous carcinoma. This study explored particularly the occurrence of uterine papillary serous carcinoma, as well as other endometrial cancers, following risk-reducing salpingo-oophorectomy in women with a BRCA1 or BRCA2 germline mutation attending a tertiary multidisciplinary clinic. A consecutive series of women with a BRCA1 or BRCA2 mutation who had undergone risk-reducing salpingo-oophorectomy without hysterectomy at the University Medical Center Groningen from January 1996 until March 2012 were followed prospectively. They were crossed with the histopathology list of endometrial cancer diagnoses reported by the Dutch nationwide pathology database PALGA. To assess the risk of endometrial cancer, a standardized incidence ratio was calculated comparing the observed with the expected number of endometrial cancer cases. Overall, 201 BRCA1 and 144 BRCA2 mutation carriers at a median age of 50 years (range, 32-78) were analyzed. After a median follow-up period of 6 years, after risk-reducing salpingo-oophorectomy, two cases of endometrial cancer were diagnosed, whereas the expected number was 0.94 cases (standardized incidence ratio 2.13; 95% confidence interval 0.24-7.69; P=0.27). Both endometrial cancer cases were of the endometrioid histological subtype. We showed that the incidence of endometrial cancer following risk-reducing salpingo-oophorectomy, especially uterine papillary serous carcinoma, in women at high-risk of developing pelvic high-grade serous carcinoma is not increased. On the basis of our data, the hypothesis of serous endometrial intraepithelial carcinoma being an important precursor lesion of pelvic high-grade serous carcinoma seems unlikely. There is no need to add a prophylactic hysterectomy to risk-reducing salpingo-oophorectomy in BRCA1 or BRCA2 mutation carriers.