Oophorectomy associated with decreased cancers in BRCA mutations

Clinical question How effective is prophylactic oophorectomy in preventing breast or ovarian cancer in women with BRCA1 or BRCA2 mutations?

Bottom line Prophylactic oophorectomy in women with BRCA1 or BRCA2 mutations is associated with a 50% reduction in the risk of developing breast cancer and an 80% reduction in the risk of developing ovarian cancer. (Level of evidence = 3a)

Synopsis These authors searched PubMed to find studies comparing prophylactic oophorectomy with no oophorectomy to prevent breast or ovarian cancer in women with mutations of BRCA1 or BRCA2 gene. They also contacted researchers and consortia to identify unpublished data. The authors don't report the following procedures associated with high-quality systematic reviews and meta-analyses: independent assessment of study eligibility, independent assessment of study quality, or independent extraction of data. Not surprisingly, they identified no randomized trials. They found 10 studies (with more than 9,000 women) that included a comparison group: two case-control studies, four retrospective cohort studies, and four prospective cohort studies. Given this kind of methodologic heterogeneity, many researchers would have stopped and simply reported the findings as a systematic review. These authors, however, chose to pool the study results to get a “fruit salad” net effect. After pooling the results, these researchers estimated that prophylactic oophorectomy was associated with a 50% reduction in the risk of developing breast cancer and an 80% reduction in the risk of developing ovarian cancer. The ovarian cancers that develop in women after an oopherectomy are usually peritoneal cancers that are histologically the same as ovarian cancer. The reporting of results in this paper do not allow for estimating absolute rates of events.