Nearly 70% of women who underwent a double mastectomy didn’t have the major genetic or familial risk factors that would indicate contralateral disease, a study found, although having an MRI during the diagnosis did lead to more of the surgeries.
The growing use of MRI as part of the diagnostic workup in patients with breast cancer may detect occult lesions for which treatment is not likely to improve outcomes for patients, study authors noted, so they conducted a longitudinal survey of women newly diagnosed with breast cancer in Detroit and Los Angeles registries from June 1, 2005, to Feb. 1, 2007, and again 4 years later.
Results appeared in JAMA Surgery.
Of the more than 1,400 women in the analysis, 18.9% strongly considered double mastectomy, or contralateral prophylactic mastectomy (CPM) and 7.6% underwent the procedure. Of those who strongly considered double mastectomy, 32.2% received it. But, the majority of patients (68.9%) who received double mastectomy had no major genetic or familial risk factors for contralateral disease.
Among the rest of the 1,400 women who didn’t undergo double mastectomy, 45.8% underwent unilateral mastectomy and 22.8% received breast conservation surgery.
Undergoing double mastectomy was significantly associated with having undergone genetic testing (vs. unilateral mastectomy, relative risk ratio [RRR]: 10.48; 95% CI, 3.61 to 3.48 and vs. breast conservation surgery, RRR: 19.10; 95% CI, 5.67 to 56.41; P<0.001).
A strong family history of breast or ovarian cancer was significantly associated with double mastectomy (vs. unilateral mastectomy, RRR: 5.19; 95% CI, 2.34 to 11.56 and vs. breast conservation surgery, RRR: 4.24; 95% CI, 1.80 to 9.88; P=0.001).
Having undergone MRI was significantly associated with double mastectomy (vs. unilateral mastectomy RRR: 2.07; 95% CI, 1.21 to 3.52 and vs. breast conservation surgery, RRR: 2.14; 95% CI, 1.28 to 3.58; P=0.001).
Also, associated factors included higher education (vs. unilateral mastectomy, RRR: 5.04; 95% CI, 2.37 to 10.71 and vs. breast conservation surgery, RRR: 4.38; 95% CI, 2.07 to 9.29; P<0.001), and greater worry about recurrence (vs. unilateral mastectomy, RRR: 2.81; 95% CI, 1.14 to 6.88 and vs. breast conservation surgery, RRR: 4.24; 95% CI, 1.80 to 9.98; P=0.001).
Worry about recurrence appeared to drive decisions for double mastectomy although the procedure has not been shown to reduce recurrence, the authors noted.
“Educational materials and decision tools for average-risk patients making initial breast cancer treatment decisions typically do not include information about CPM, actual risk of contralateral breast cancer, or interpretation of genetic test results. Such information could be useful for women making these decisions,” the authors wrote. “However, our findings that CPM was strongly associated with higher educational attainment suggests that improved knowledge may not be sufficient to address patient factors, such as worry about recurrence, motivating strong consideration of the procedure. Furthermore, the association found between diagnostic MRI and receipt of CPM indicates a need to consider strategies for educating both patients and clinicians about the impact of extensive testing on treatment decision making.”
An invited commentary stated that decisions about double mastectomies are made at an emotional time that make it difficult to balance the true risks and benefits. Better shared-decision making is needed. “While CPM might be considered overtreating women without clinical indications, it might still be the right choice for some women for risk reduction, cosmetic, and/or emotional reasons.”