ASBrS 2017: Contralateral Prophylactic Mastectomy (CPM)
By: Alicia
May 8, 2017

ASBrS17: Contralateral Prophylactic Mastectomy (CPM)

This guest post is by Dr. Diane Radford.

The American Society of Breast Surgeons published a consensus statement on CPM in which it was stated that average-risk women with unilateral breast cancer do not derive any oncologic benefit from CPM, and thus CPM should be discouraged (Annals of Surgical Oncology 2016;23:1300-1305). The ABIM Foundation Choosing Wisely Campaign states double mastectomy does not improve the success of treatment or replace the need for other therapies, such as radiation or chemotherapy.

In a podium presentation researchers from Memorial Sloan Kettering Cancer Center (MSKCC) presented their findings on contralateral breast cancer risk following a diagnosis of DCIS. As background, according to the National Cancer Data Base (NCDB), between 1998 and 2007 the rate of CPM for DCIS rose from 2% to just over 6%. Miller ME et al (Proceedings 254421, page 21) examined the prospectively managed MSKCC DCIS database covering 1978-2011. The identified 2,759 patients who underwent breast conserving surgery for DCIS and thus had a contralateral breast at risk. At a median follow up of just under 7 years, 4.2% of those at risk developed contralateral breast cancer (CBC), 11.2% has an in-breast tumor recurrence (IBTR), and 1.2% had both CBC and IBTR. On multivariate analysis, administration of endocrine therapy after initial diagnosis significantly reduced the risk of CBC and IBTR, cutting it by 50%. They concluded that risk of CBC was low across all patient groups, and that the 10-year IBTR rate was 2.5-fold higher than the rate of CBC, 4-fold higher in those not receiving radiation after their breast conserving surgery. In addition, while factors associated with IBTR risk are important in decision making regarding management of initial DCIS, they are not an indication for contralateral prophylactic mastectomy.

Judy Boughey and others from the Mayo Clinic in Rochester analyzed CPM from the cost point of view (Proceedings 25692, page 35). Of all of therapeutic mastectomies, the majority (circa 45% in 2014) are bilateral with immediate breast reconstruction. The rate of bilateral versus unilateral mastectomy has been increasing over time (see figure).

They sought to determine the two-year health care utilization and total costs for unilateral mastectomy (UM +IBR) with reconstruction versus bilateral mastectomy with reconstruction (BM+IBR). Looking at administrative claims data from a large U.S. commercial insurance database, OptumLabs, over 11,000 women were identified who underwent immediate breast reconstruction. BM + IBR (whether implant or flap reconstruction) resulted in longer hospital length of stay, more visits to the ER, and higher total cost of care over two years. The researchers recommended that patients considering CPM with reconstruction