Progesterone altering drug could reduce risk of aggressive breast cancer

New research co-led by scientists at UCL, found that existing drugs modifying the effect of the hormone progesterone, such as mifepristone, could reduce the risk of aggressive "triple negative" breast cancer in women with an alteration of the BRCA1 gene. Triple-negative breast cancer (TNBC) is most common in women who have a BRCA1 mutation and this type of cancer affects 13 in every 100,000 women. Outcomes for those diagnosed with TNBC are poorer because these cancers are more aggressive and more likely to recur than other cancers. Further, the cells making up the cancer do not display common drug targets (o estrogen or progesterone receptors  and a protein called HER2 ) and hence treatment options are limited. In an initial, pilot study, published in Genome Medicine, scientists conducted a detailed evaluation of progesterone levels in women with a BRCA mutation, and examined the effect of drugs targeting progesterone on the risk of developing breast cancer in women known to be at risk. In 17 women (9 with a BRCA1 mutation vs 8 without), oestrogen or progesterone levels were measured daily using saliva samples. Researchers found that levels of progesterone were higher throughout the menstrual cycle, and particularly during the luteal phase, in women with BRCA1 gene alterations.