No Surgery for Low-Grade Ductal Carcinoma In Situ?

Abstract

Since the more widespread use of routine screening mammography, the incidenceofductal carcinoma in situ (DCIS)has increased dramatically and accounts for about 20% to 30%of all newly diagnosed breast cancers.1 Deaths from breast cancer among women with DCISmayoccur fromunidentified invasive disease at the time of diagnosis, progression of inadequately excised DCIS, or the development of an independent recurrent invasive breast cancer.2 Our current inability to accurately predict which women with DCIS are at the greatest risk for developing invasive disease generally necessitates thatallpatientsdiagnosedashavingDCISundergo treatment. Despite the relatively benign course of DCIS, most women undergo aggressive surgical and radiation treatment. The risk of overtreatment has been recognized.2 Sagaraetal3usedapropensityscoreanalysis toevaluate the survivaloutcomesofpatientswithDCIS intheSurveillance,Epidemiology, andEndResultsdatabaseandconcluded that there wasnosurvival benefit for surgical excisionof low-gradeDCIS. Therewasasurvivalbenefit forsurgicalexcisioninpatientswith intermediate-orhigh-gradeDCIS.Therefore,Sagaraetal3questiontheneedandbenefit forsurgicalexcisionof low-gradeDCIS. We urge physicians to exercise cautionwhen generalizing this population-basedcohort analysis to currentpractice.Thereare inherent limitationstopopulation-basedcancerdatawithregard to specificpatient and tumorcharacteristics. For example, 14% of the nonoperative group received radiation therapywithout undergoingsurgicalexcision.This isnotastandardapproachfor DCISandthedetailssurroundingthesediscrepanciesarenotclear withintheSurveillance,Epidemiology,andEndResultsdatabase. Inaddition, it is impossible todeterminehowmanywomenmay havehadan initial diagnosis ofDCISbasedon their coreneedle biopsy but who then had an upgrade to invasion on final excision.Thosepatientswouldhavebeenexcludedfromthisanalysis. Most importantly, we argue that DCIS grade is not an appropriate surrogate for genomic profile and biologic outcomes. Molecular markers that provide prognostic and predictive informationhold themostpromise for tailoring therapy on an individual level. The 21-gene recurrence score for estrogen receptor–positive invasive breast cancer was used as a benchmark for the development of a 12-gene subset that has been used to develop and validate a DCIS score that divides patients into low risk, intermediate risk, and high risk for 10year local in-breast recurrence.4 Multivariable models of risk for ipsilateral breast events both excluding and including the DCIS scorehavebeenperformed.Tumor size,menopausal status, andDCIS scorewere the only factors significantly associatedwith risk for an ipsilateral breast event. Tumor grade and thepresenceof comedonecrosiswerenot associatedwith risk for ipsilateral breast events.4 The ability to profile entire tumor genomes relatively quickly and affordablywill aid our understanding of the relationship between DCIS and invasive disease so that targeted approaches can be taken. We advocate for less treatment in those patients who have a low risk for invasive recurrence and/or progression. That knowledge is unlikely to come from our standard clinicopathologic characteristics. For now, surgeons should hold onto their scalpels.