Trends in Close Margin Status and Radiation Therapy Boost in Early Stage Breast Cancer Treated with Breast Conserving Therapy

Document Type

Conference Proceeding

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International Journal of Radiation Oncology Biology Physics


Purpose/Objective(s): The Society of Surgical Oncology and American Society for Radiation Oncology released a consensus statement in 2014 (later endorsed by Choosing Wisely in 2016) recommending “no tumor on ink” as an adequate margin for breast cancer treated with lumpectomy. This guideline targeted patients with close margins (CM, i.e. 2 mm or less) in order to decrease rates of re-excision, improve cosmetic outcomes, and decrease costs. We hypothesize that a consequence of this policy would be an increased rate of CM and corresponding increase in radiation therapy boost (RTB) utilization to compensate.

Materials/Methods: A statewide, multi-institutional consortium of up to 26 academic and community clinics prospectively collected patient level data from 2012 – 2019 of breast cancer patients treated with breast conserving therapy. For this analysis, inclusion criteria included T0-3 disease, lumpectomy for initial surgical management, pathologic margin of 2 mm or less, and use of adjuvant radiation therapy (either conventional [CFX] or accelerated [AFX] fractionation with or without boost). Chi-square testing was used to compare time periods.

Results: A total of 12,499 pts were in the database from which CM was identified in 383/2480 DCIS pts (15.4%) and 1110/10019 carcinoma pts (11.1%). Comparing pre- and post- Choosing Wisely endorsement (2012-2016 vs. 2017-2019), rates of CM decreased for both DCIS and carcinoma (13.9% vs. 9.5%, p<0.0001) as did overall rates of RTB (84.1% vs. 79.8%, p<0.0001). However, trends in RTB differed based on fractionation: CFX was stable (94.1% vs. 94.2%, p = 0.0862) whereas AFX had increased (69.2% vs. 74.2%, p<0.0001). RTB for the CM subset (CFX and AFX) were steady over these time periods.

Conclusion: Despite a loosening of margin requirements through consensus guidelines and campaigns, there has actually been a decrease in both rates of CM and overall RTB. Trends in RTB differed by fractionation (CFX stable, AFX increase) which were independent of rates of CM. [Formula presented]





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