Is tamoxifen absolutely contraindicated in pre-menopausal women with Lynch syndrome?

Given a genetic confirmation of Lynch Syndrome, risk reduction surgery should be performed. This is especially true with those Lynch cohorts with MSH6 mutations or MSH2, as these have the highest risk---or even the exclusive presentation with--endometrial cancers. Once the uterus has been removed, tamoxifen may be employed if indicated.

Women with Lynch syndrome can have up to a 40-60% lifetime risk of endometrial cancer depending on the mutation (Cancer Control 2009). A small number (1%) of women in the Lynch syndrome registry of over 1000 pts reported tamoxifen or raloxifene, so the effect of SERMs on this population is not known (JAMA 2015). If the patient underwent prophylactic TAH/BSO, then I would treat with tamoxifen or an AI as clinically warranted. If she still has her uterus and is undergoing surveillance, then I would favor using raloxifene or AI for chemoprevention. For DCIS/IDC with an intact uterus I would favor doing AI +/- OFS if anti estrogen treatment is indicated.The estrogen deprivation will reduce endometrial proliferation as well. There was one case o...