Background/Objectives: High-grade serous carcinoma (HGSC) is the leading cause of ovarian cancer-related mortality. It usually arises from fallopian tube epithelium, with a smaller subset arising in non-tubal sites including the ovary or peritoneum. The origin of HGSCs without evidence of tubal involvement remains unclear. Moreover, in women with genetic predisposition to developing HGSC, the additional protection afforded by prophylactic removal of the ovaries in addition to the fallopian tubes has not yet been established. Methods: We used a well-characterized genetically engineered mouse model (GEMM) of oviductal HGSC based on conditional, somatic inactivation of the Brca1, Trp53, Rb1, and Nf1 tumor suppressor genes (BPRN mice) to compare preventive effects for HGSC via bilateral salpingectomy versus bilateral salpingo-oophorectomy. We also explored the origins of non-tubal HGSCs in ectopic tubal-type epithelium (endosalpingiosis) present in the mouse ovaries and peritoneum. Results: While bilateral salpingectomy significantly reduced the incidence of HGSCs in the GEMM model, bilateral salpingo-oophorectomy completely prevented tumor development. We identified an example of HGSC with apparent origin in endosalpingiosis, implicating endosalpingiosis as a likely precursor for non-tubal HGSC. Conclusions: Our findings confirm the superiority of bilateral salpingo-oophorectomy over salpingectomy alone in reducing HGSC risk and affirm the rationale for surgical strategies to reduce HGSC risk in women carrying pathogenic variants of BRCA1/2 and other genes associated with homologous recombination deficiency. Our findings also illustrate how work with GEMMs can advance new insights into HGSC pathogenesis.
Zhai et al. (Sun,) studied this question.