Microscopic Screening of Reduction Mammoplasties Risks Overdiagnosis

The study by Ambaye et al¹  aptly demonstrates what many have known about cancer detection for decades: the more you look, the more you find. The authors' recommendation to extensively sample breast tissue obtained from older women undergoing reduction mammoplasty, however, deserves more scrutiny. They sampled 11 breast sections in each patient and found 14 cancers (whether the 6 cases of lobular carcinoma in situ should be included is a relevant question). But why stop here? There is little doubt that sampling 25 sections would detect more cancer.

Physicians increasingly recognize that the goal is not to find as many cancers as possible, but instead to find the cancers that matter. Cancers detected by this microscopic screening process are bound to be small, in this study less than half a centimeter on average. The detection of asymptomatic, microscopic neoplasia only increases the risk of overdiagnosis—the detection of “cancers” not destined to cause harm or death in that patient.

The findings of Ambaye et al¹  align with those of others, suggesting there is a substantial population “reservoir” of asymptomatic breast cancers, many of which will not become deadly.²  A previous study³  has shown that detection of asymptomatic small breast cancers (<2 cm) is more likely to result in overdiagnosis than in reduction of advanced lesions. Intriguingly, there are epidemiologic data suggesting that some small breast cancers not only remain indolent but may actually regress.^4,5 

Clinicians look to pathologists to play an umpire role in medicine—to make the “call” of cancer versus not cancer. But pathologists understand that the real world is not dichotomous and that the “call” is influenced by both diagnostic thresholds and the degree of scrutiny. Microscopic screening will identify multiple abnormalities even in “healthy” patients: in this study 9.8% of women had significant pathologic findings. Microscopic screening can also lead to a cascade of medical interventions: these women received more visits, more imaging, and more treatment. Increased intervention is not the end goal for patients, who instead wish for longer and better life. Pathologists should similarly not view diagnosis of cancer as the end goal but align their practice to improve these patient-centered outcomes. There are no data to suggest that the detection of microscopic breast lesions achieves this goal. In particular, the best course of action for “risk factor” diagnoses like atypical lobular hyperplasia or lobular carcinoma in situ, which constituted most of the findings, is even less clear.

Ideally, a microscopic screening program such as the one recommended here would be evaluated in a randomized trial before implementation. Given what we now know about small breast cancers, we doubt it would pass such a rigorous evaluation. Others might disagree. Perhaps we can agree that pathologists should obtain informed consent before microscopic screening. A woman should know not only that an important cancer might be found, but also that overdiagnosis is more likely. While pathologists are not accustomed to seeking explicit patient consent for their work, microscopic screening of an asymptomatic patient presumably has a different benefit to harm ratio than when a patient presents with a specific diagnostic concern, signifying the need for increased shared decision-making. Patients should also consent to the additional expense and the potential lifetime of downstream costs—a portion of which are increasingly likely to come out of their pocket.