PREVENTION IN PILL FORM
Did you know that several medications to treat breast cancer have been shown to stave off the disease in healthy women? “Of all the big cancers, there’s only one that can be prevented with medications, and that’s breast cancer,” says Dr. Julian Kim at CancerCare Manitoba. Tamoxifen and raloxifene, which block estrogen receptors in breast cells, provide up to a 50 per cent reduction in relative risk. Exemestane and anastrozole lower residual levels of estrogen in postmenopausal women, resulting in an up to 65 per cent relative risk reduction.
This matters if your risk happens to be higher than average. In 2015, an international study of over 67,000 women resulted in a new breast cancer risk calculator. Called the polygenic risk score (PRS), it takes into account what’s in your genes—not whether you carry a BRCA gene mutation, which accounts for less than 10 per cent of breast cancer cases, but whether a particular set of spelling mistakes in your genome is associated with greater or lower odds of developing breast cancer.
Currently, Kim is leading a breast cancer prevention trial in which women will be assessed regarding their decision to use or to forgo preventative medications, then shown different ways of lowering their risk. For some women, increasing exercise and making healthier diet choices may be sufficient. But those with a higher PRS may also choose to take medication. For them, side effects, such as hot flashes, may be well worth it.