Tamoxifen has been used for several years as adjuvant therapy for women diagnosed with breast cancer. Tamoxifen was introduced already in the 1970s and reduces the risk of breast cancer recurrence with approximately 30%. Recent studies also indicate that use of Tamoxifen as primary prevention for healthy women at high risk reduce breast cancer incidence.
Despite the remarkable risk reduction in preventive studies, primary preventive strategies are scarcely part of clinical routine. There are several possible reasons for the reluctance. The major one being that the side effects of these therapies are not trivial. Serious side effects could only be acceptable for those that benefit from therapy, that is, there is a need of identifying women at high risk.
Also, there is not a consensus on dose needed in the preventive setting. So far only full therapeutic dose has been tested and no attempts have been made to determine if lower doses prevent women from being diagnosed with breast cancer.
As a first step toward a larger prospective study the Karma group are now planning to launch a randomized, double-blind, placebo controlled trial to investigate the mammographic density reduction at different doses of Tamoxifen.
Our aim is to identify an optimal Tamoxifen dose for reducing risk of breast cancer. Mammographic density reduction will be used as a proxy for therapy response and thereby indirectly incidence.
A pilot study started march 2015 and is ongoing. A roll-out of a full scale trial is planned to be be launched during 2016.