Patient Prognostic Score and Associations With Survival Improvement Offered by Radiotherapy After Breast-Conserving Surgery for Ductal Carcinoma In Situ: A Population-Based Longitudinal Cohort Study

Abstract

Radiotherapy (RT) after breast-conserving surgery (BCS) is a standard treatment option for the management of ductal carcinoma in situ (DCIS). We sought to determine the survival benefit of RT after BCS on the basis of risk factors for local recurrence. Patients and MethodsA retrospective longitudinal cohort study was performed to identify patients with DCIS diagnosed between 1988 and 2007 and treated with BCS by using SEER data. Patients were divided into the following two groups: BCS+RT (RT group) and BCS alone (non-RT group). We used a patient prognostic scoring model to stratify patients on the basis of risk of local recurrence. We performed a Cox proportional hazards model with propensity score weighting to evaluate breast cancer mortality between the two groups. ResultsWe identified 32,144 eligible patients with DCIS, 20,329 (63%) in the RT group and 11,815 (37%) in the non-RT group. Overall, 304 breast cancer-specific deaths occurred over a median follow-up of 96 months, with a cumulative incidence of breast cancer mortality at 10 years in the weighted cohorts of 1.8% (RT group) and 2.1% (non-RT group; hazard ratio, 0.73; 95% CI, 0.62 to 0.88). Significant improvements in survival in the RT group compared with the non-RT group were only observed in patients with higher nuclear grade, younger age, and larger tumor size. The magnitude of the survival difference with RT was significantly correlated with prognostic score (P , .001). ConclusionIn this population-based study, the patient prognostic score for DCIS is associated with the magnitude of improvement in survival offered by RT after BCS, suggesting that decisions for RT could be tailored on the basis of patient factors, tumor biology, and the prognostic score.

Risk of death from breast cancer after treatment for ductal carcinoma in situ

“…This implies that, at least in some patients, local control does make a difference. Sagara and colleagues examined the benefit of RT stratified by factors associated with risk of recurrence. In women of younger age, and those with tumours of a higher nuclear grade or larger size, breast cancer survival was significantly better after BCS and RT compared with BCS alone.…”

Wherein the Authors Attempt to Minimize the Confusion Generated by Their Study “Breast Cancer Mortality after a Diagnosis of Ductal Carcinoma In Situ” by Several Commentators Who Disagree with Them and a Few Who Don’t: A Qualitative Study

“…Nevertheless, many commentators misinterpreted the finding of low mortality to infer either that dcis is a precursor, and not a cancer [15][16][17][18] ; that dcis is overdiagnosed and does not need to be treated (that is, "watch and wait") [19][20][21][22][23][24][25][26][27][28][29] ; or that dcis is overtreated (that is, omit radiotherapy) [30][31][32][33][34] . Most troubling from our point of view was that several commentators interpreted the finding that the increased risk of death from breast cancer in dcis patients who developed an ipsilateral invasive recurrence justified efforts to prevent the invasive ipsilateral recurrence as a life-saving measure [35][36][37][38][39][40][41][42][43] . Only 5 of the 50 articles referenced our paper in the intended context: that is, that dcis can metastasize, or that breast cancer is a systemic disease that disseminates and metastasizes early [44][45][46][47][48] .…”

Challenges in Radiotherapy

“…However, some controversy exists whether RT is mandatory in an exclusively low-risk constellation, like small tumor sizes (<2.5 cm), low-grade differentiation (G1–2), and >60 years of age [16] which has been shown to be beneficial in terms of local control by the RTOG-9804 trial [14], respectively. Therefore, we are offering RT to all DCIS patients after BCS.…”