(P027) Increasing Use of Postlumpectomy Radiotherapy for Ductal Carcinoma In Situ of the Breast in the United States

Yi An, MD, Henry S. Park, MD, MPH, John M. Stahl, MD, Sue B. Evans, MD, MPH, Charles E. Rutter, MD; Yale University School of Medicine

INTRODUCTION: Breast ductal carcinoma in situ (DCIS) is a preinvasive neoplasm historically treated with mastectomy prior to the adoption of the breast conservation paradigm. Although postlumpectomy radiation therapy (RT) for DCIS reduces local recurrence risk, its role in patients with favorable-risk disease is controversial. As such, RT utilization rates for DCIS may vary. Here, we are the first to study the change in usage of postlumpectomy RT for DCIS and the factors associated with these changes on a national level.

METHODS: We identified patients diagnosed with DCIS and treated with lumpectomy between 1998 and 2011 within the National Cancer Database. Chi-square tests and multivariate logistical regression analyses were used to identify demographic, tumor, and treatment facility factors associated with increased likelihood of receiving postlumpectomy RT.

RESULTS: We identified 144,861 DCIS patients who underwent lumpectomy. Median age was 59 years, 84% of patients were white, and 39% had high-grade disease. A total of 99,639 (69%) women received postlumpectomy RT. The proportion receiving postlumpectomy RT increased from 61% in 1999 to 72% in 2008 (P < .01). Statistically significant predictors of postlumpectomy RT included younger age, higher grade, fewer comorbidities, rural residence, and increased distance from treatment center (P < .01 for all). Interestingly, medium-sized tumors and negative surgical margins were also significant predictors of postlumpectomy RT relative to patients with larger tumors and positive margins, suggesting that these higher-risk patients may undergo complete mastectomy rather than receive adjuvant radiotherapy.

CONCLUSION: The percentage of DCIS patients receiving postlumpectomy RT increased between 1999 and 2008. Younger patients with higher grade, medium-sized tumors, and fewer comorbidities were more likely to receive postlumpectomy RT.

Proceedings of the 97th Annual Meeting of the American Radium Society -americanradiumsociety.org