6 year prospective Canadian study following 1492 women in 365 families. All negative for BRCA1 and 2 mutations. Families followed up had 2 or more breast cancer diagnosis under 50y or 3 diagnosis at any age. 65 women developed breast cancer instead of the expected 15 expected for a population without a family history. Giving a four fould increased risk. Compared to the presence of BRCA1/2 mutations which confer a 7 fold increased risk.
Important to take the family history especially in women. Tamoxifen as prophylaxis? Quick research: it is a licenced indication ( 20mg qd x5 years according to epocaratesRx) but need to weigh up increased risk of stroke, PE and uterine malignancies. When is someone going to design an easy to use risk comparison tool?