C. E. Jones1, B. E. Jackson1, H. Krontiras1, M. M. Urist1, K. I. Bland1, C. C. Parker1 1University Of Alabama at Birmingham,Surgical Oncology,Birmingham, Alabama, USA
Introduction:
To reduce the risk of locoregional recurrence for patients with ductal carcinoma in situ (DCIS) following mastectomy with close (<2mm) or positive margins, many advocate for postmastectomy radiation therapy (PMRT). However, the impact on overall survival is unknown. We aim to characterize the different management practices of DCIS throughout the country in patients who undergo mastectomy with close or positive margins.
Methods:
Using the 2004-2013 National Cancer Data Base, we identified all female patients with a diagnosis of DCIS who underwent mastectomy. Distributional characteristics were summarized for the overall and margin stratified samples. Characteristic differences were assessed by region and receipt of radiation. Chi-square and independent sample t-tests were used to assess differences for categorical and continuous variables, respectively.
Results:
Out of a total of 2,032,209 patients, we identified 21,591 patients who met inclusion criteria. The average age was 56, and the patients were predominantly white (80.2%), lived in metropolitan areas (86.7%), and received treatment at a Comprehensive Community Cancer Program (53.4%) or Academic/Research Program (28.7%). Patients were predominantly from the South (42.1%), followed by Midwest (24.7%), West (17.2%), and Northeast (15.9%) regions. Most patients underwent unilateral mastectomy (65.2%) with reconstruction (51.7%). Although most tumors were ER positive (77.3%) and/or PR positive (65.9%), only 17.6% of patients were treated with adjuvant endocrine therapy. Endocrine therapy significantly differed by region (p < .001) and was most common in the Midwest (20.6%) followed by Northeast (18.4%), South (16.7%), and Western regions (15.6%).
Tumors with close/positive margins were identified among 470 patients (2.2%). Patients with negative margins were older at diagnosis (56 vs. 53; p < 0.001) and more frequently in the Northeast or Western regions (p < 0.001). They were more likely to undergo a contralateral prophylactic mastectomy (34.9% vs. 30.4%; p = 0.043) with reconstruction (51.9% vs. 43.8%; p < .001). Among the 470 patients with close/positive margins, 78 (17.5%) received PMRT. Patients who received PMRT were on average 4 years younger (50 vs. 54; p = 0.012) and from the Midwest or Northeast regions (p = 0.010). Overall, patients who had close/positive margins were not significantly more likely to receive endocrine therapy. However, patients with close/positive margins who underwent PMRT were more likely to also receive endocrine therapy (29.2% vs. 18.6%; p = 0.043).
Conclusion:
Postoperative management of DCIS in patients who undergo mastectomy with close or positive margins remains controversial. There is no apparent consensus regarding PMRT across the country based on this analysis of a large national cancer database. Differences in treatment patterns reinforce a need to determine whether PMRT improves survival in order to establish treatment guidelines.