Guidelines Told Surgeons to Stop, But Rates of Preventive Mastectomy Barely Budged

When the American Society of Breast Surgeons issued a consensus statement in 2016 urging surgeons to discourage contralateral prophylactic mastectomy, or CPM, in women with unilateral breast cancer at average risk of a second malignancy, the expectation was that a procedure once described as a trend toward more aggressive surgical treatment would finally begin to recede. A new retrospective study published in Breast Cancer Research and Treatment suggests that, at least at two major academic centers, that expectation has not been met. Researchers led by Anna M. Reagan and Erin E. Burke reviewed the records of 6,203 women diagnosed with stage 0 to III unilateral breast cancer who underwent surgery between 2011 and 2020 at the University of Kentucky and within the University of Minnesota academic health system, dividing them into a pre-guideline cohort of 2,619 patients diagnosed between 2011 and 2015 and a post-guideline cohort of 3,584 patients diagnosed between 2016 and 2020. What they found was a striking disconnect between professional consensus and surgical practice.

The headline finding is deceptively simple: CPM rates barely moved. In the earlier cohort, 19 percent of women had their healthy opposite breast removed at the time of cancer surgery; in the later cohort, the figure was 15 percent, a statistically significant but clinically modest decline that leaves roughly one in seven patients still undergoing a procedure that society guidelines explicitly discourage for average-risk women. The study period is particularly instructive because it brackets the 2016 consensus statement, which synthesized data showing that CPM produces only a small absolute reduction in contralateral breast cancer and no demonstrated survival benefit for most patients. Subsequent work has reinforced that message, including a 2024 analysis in JAMA Oncology reporting that bilateral mastectomy did not improve breast cancer mortality, and a Society of Surgical Oncology statement published the same year laying out narrow indications, outcomes, and risks for contralateral mastectomy. Yet the Kentucky and Minnesota data show that the practice, once entrenched, has proven resistant to guideline-driven de-escalation.

The technical details of the study design matter for interpreting these numbers. Because the analysis was a retrospective chart review rather than a randomized trial, it captures real-world practice patterns but cannot establish causation between the 2016 statement and any change in surgical behavior. The two cohorts were defined by diagnosis date, and the researchers evaluated not only CPM rates but also the uptake of genetic testing and the clinical and demographic factors associated with the decision to remove the contralateral breast. The institutions are both academic health systems, which typically have greater access to genetic counseling and multidisciplinary tumor boards than community hospitals, making the persistence of high CPM rates all the more notable. If guideline concordance is difficult to achieve in settings with robust resources, the authors suggest, the challenge in broader practice may be even greater.

The most dramatic change between the two eras was not in the operating room but in the genetics laboratory. Before 2016, only 2 percent of the women in the study underwent genetic testing; from 2016 onward, that figure rose to 22 percent. This eleven-fold increase reflects the second major consensus statement from the American Society of Breast Surgeons, published in 2019, which recommended that genetic testing be made available to all patients with breast cancer, not merely those meeting traditional family-history criteria. The expansion was enabled by broader panel testing that now screens for a growing list of moderate-penetrance genes such as ATM, CHEK2, and PALB2 in addition to the high-risk BRCA1 and BRCA2 genes. Wider testing has real clinical value, identifying carriers who benefit from intensified surveillance or risk-reducing surgery, but it has also complicated surgical decision-making, because the contralateral breast cancer risk associated with many moderate-risk variants remains imprecisely quantified.

Genetic testing emerged as one of the strongest factors associated with receiving a CPM in this cohort. That association cuts both ways. For women found to carry a pathogenic variant with a substantially elevated contralateral risk, such as BRCA1 or BRCA2, prophylactic removal of the unaffected breast is guideline-supported and can meaningfully reduce second cancer risk, as established by long-term studies of mutation carriers. But prior research has shown that testing results often arrive too late in the surgical pathway to change decisions, and that many women with negative test results still proceed with CPM. Studies of rapid preoperative testing have demonstrated that timely results can de-escalate surgery among carriers, yet the present findings suggest that in routine practice, testing more often accompanies, rather than redirects, the decision toward more extensive surgery. The authors point to this timing problem as a key target for intervention.

The demographic and tumor characteristics associated with CPM form a familiar but troubling pattern. Younger age at diagnosis, white race, lobular histology, increasing tumor size, and HER2 positivity all independently predicted receipt of the procedure. The age effect is consistent with a large body of literature showing that younger women more frequently overestimate their risk of a contralateral cancer and place greater weight on future risk when making surgical choices. The racial disparity is more concerning: prior national analyses have documented that white patients are disproportionately likely to undergo CPM even after accounting for clinical factors, raising questions about equitable counseling and access to reconstruction. The association with lobular histology likely reflects both the genuine difficulty of surveillance in lobular carcinoma, which is harder to detect mammographically, and the tendency of lobular cancers to be multifocal, which may amplify patient and physician concern about the opposite breast.

The persistence of CPM despite discouraging guidelines is not unique to this study. Analyses from the National Cancer Data Base and from state and national registries documented the steep rise of the procedure through the 2000s, and subsequent single-institution and multi-institution studies have repeatedly found that rates plateaued rather than fell after 2016. Research examining the effect of the American Society of Breast Surgeons guidelines specifically, including work published in Annals of Surgical Oncology and in Surgery, reached similar conclusions: the statements changed the conversation but not, for the most part, the operations. Patient-driven factors appear central. Surveys have shown that many women who choose CPM report high satisfaction with the decision, and studies of patient reactions to surgeon recommendations indicate that surgeon advice is only one input among many, with fear of recurrence and a desire for symmetry after reconstruction playing powerful roles.

The clinical stakes of this disconnect are considerable. CPM is a major operation that extends anesthesia time, increases the risk of surgical complications, lengthens recovery, and can compromise or delay reconstruction, all for a benefit that for average-risk women is largely psychological rather than survival-related. Quality-of-life studies comparing breast conservation with mastectomy and reconstruction have generally found comparable or better long-term outcomes with the less aggressive approach, and decision analyses have shown that the survival gain from CPM in average-risk women is measured in fractions of a percent. At the same time, the rise of multigene panel testing means that a minority of patients genuinely benefit from the procedure, which complicates blanket discouragement and may partly explain why surgeons remain reluctant to refuse a requested CPM outright. The clinical challenge is discriminating between the woman whose panel result justifies bilateral surgery and the woman whose fear, not genetics, is driving the request.

The authors are explicit that their findings should catalyze further work rather than close the question. They call for research to understand why CPM rates have remained stable across the guideline era and to identify interventions capable of reducing rates in average-risk women. Candidate strategies suggested by the broader literature include moving genetic testing earlier in the diagnostic pathway so that results can inform the initial surgical plan, standardizing risk counseling with validated tools that communicate contralateral risk in absolute rather than relative terms, and engaging surgeons in shared decision-making frameworks that acknowledge patient values while presenting the evidence clearly. Whether such interventions can succeed where consensus statements have not remains an open question, but the two-institution data provide a clear baseline: a decade after professional societies said the procedure should be rare, one in seven women was still having it.

For patients, the practical message is that a new breast cancer diagnosis is a moment when surgical decisions are made quickly and often under emotional strain, and that the evidence favors restraint for most women. A contralateral cancer diagnosed at an early stage is generally treatable, modern systemic therapies reduce contralateral risk further, and removing the healthy breast does not improve survival for the average patient. For women with documented pathogenic variants, the calculus is different and genetic counseling is essential. The study’s most valuable contribution may be its demonstration that guidelines alone do not change practice, and that closing the gap between evidence and the operating room will require changes to how, and how early, genetic information reaches the surgical decision.

Subject of Research: Trends in contralateral prophylactic mastectomy and genetic testing among women with unilateral breast cancer following society guideline publications

Article Title: Trends in contralateral prophylactic mastectomy and genetic testing in the era of new society guidelines

Article References: Reagan, A. M., Rutherford, C. R., Prathibha, S., Levy, B. E., Praska, C., Thacker, S. E., Kolbow, M., Ozed-Williams, B., Karnik, K. N., Mangino, A. A., Marmor, S., Tuttle, T. M., Hui, J. Y. C., & Burke, E. E. (2026). Trends in contralateral prophylactic mastectomy and genetic testing in the era of new society guidelines. Breast Cancer Research and Treatment, 219(3), Article 14. https://doi.org/10.1007/s10549-026-08073-6

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08073-6

Keywords: contralateral prophylactic mastectomy, breast cancer, genetic testing, BRCA, surgical guidelines, American Society of Breast Surgeons, unilateral breast cancer, genetic counseling, mastectomy rates, breast cancer surgery, hereditary cancer, surgical decision making