Monday, October 20, 2014: 4:30 PM

Sarah T. Hawley, PhD, MPH1, Steven Katz, MD1 and Reshma Jagsi, MD, DPhil2, (1)University of Michigan, Ann Arbor VA Health System, Ann Arbor, MI, (2)University of Michigan, Ann Arbor, MI
Purpose: Concern has been raised about the growing rate of extensive breast surgery, including contralateral prophylactic mastectomy (CPM). We sought to assess patient reported factors associated with CPM decisions in a population-based sample

Methods: Newly diagnosed breast cancer patients identified from Los Angeles and Georgia SEER registries were surveyed approximately 5 months after diagnosis. Patients were asked about their surgical treatment (lumpectomy-L, unilateral mastectomy-UM, CPM), and if they had a genetic test.  Factors contributing to decision making, including knowledge about the benefit of CPM and values important to patients’ surgical decisions, were compared with surgery type using chi-square tests. Multinomal logistic regression (MNL) was ussed to assess factors associated with CPM compared to UM and L.

Results: 509 responses have been received to date (anticipated N of 1,000). Of these, 62.5% received lumpectomy, 15% UM and 22.6% CPM. Of women who had CPM, 43.4% did not have a genetic test, 45.2% had a negative test, and 11.3% had a genetic mutation. Of women without a mutation who got CPM, 36.5% thought CPM improved survival in all women with breast cancer, and 19.8% thought it would reduce risk of cancer coming back.  These women more often reported it was very important to reduce worry about recurrence when choosing their surgery than did patients who got UM or L (78.4% vs. 62.5%, 55.9%, P<0.010) but were no more likely to indicate they wanted to do everything possible. Women who were incorrect regarding survival benefit of CPM were significantly more likely than those who were correct (RRR 4.88; 95% CI 2.37-10.21) to receive CPM vs. lumpectomy.

Conclusions: In this population-based sample, rates of CPM were high and it was most often received by women without a genetic mutation. CPM decisions appear driven by a desire to reduce worry about recurrence, while also being made with low knowledge about the impact of CPM on survival and recurrence. Further work to understand decision-making for CPM in the absence of clinical indications is warranted.