Abstract PD7-03: Cost-effectiveness analysis of intraoperative radiotherapy for ductal carcinoma in situ

Background Whole breast radiation therapy (WBRT) following lumpectomy for ductal carcinoma in situ (DCIS) is standard of care, however, the risk of local recurrence with and without radiation ranges as low as 0.9% vs. 6.7% over 7 years. Intraoperative radiotherapy (IORT) is a potential alternative with advantages of decreased toxicity to adjacent organs, convenience, and improved quality of life. While prospective trials of IORT for DCIS are ongoing, the objective of this study was to estimate the cost-effectiveness of IORT vs. WBRT vs. no radiation for DCIS. Methods We developed a Markov model using TreeAge Pro 2016 to evaluate the cost-effectiveness of WBRT, IORT, and no radiation in patients with DCIS following lumpectomy. Health states included disease free, local recurrence (ipsilateral DCIS or invasive cancer), distant recurrence or death due to breast cancer, and death due to non-breast cancer causes. A 10-year time horizon and societal perspective were used. Model input parameters were derived from the literature. Costs reflected 2016 Medicare rates. The primary endpoint was incremental cost-effectiveness ratio (ICER), defined as the difference in cost, divided by the difference in quality-adjusted life years (QALYs) of two interventions. We performed analyses of subgroups defined according to DCIS risk (histologic grade, Oncotype Dx® DCIS recurrence score, low risk per RTOG 9804 criteria) and endocrine therapy use (none, tamoxifen, aromatase inhibitor). Sensitivity analyses explored uncertainty in the model. Results IORT was the most cost-effective strategy, with an increase of 0.18 QALYs at an incremental cost of $4,728, corresponding to an ICER of $26,943/QALY when compared with no radiation therapy. WBRT resulted in an increase in 0.18 QALYs at an incremental cost of $6859, corresponding to an ICER of $39,085/QALY. For both strategies, the ICERs did not exceed the willingness to pay (WTP) threshold of $100,000. IORT remained the most cost-effective strategy across DCIS risk groups, but was more cost-effective in higher risk patients, as demonstrated by lower ICERs. In low risk DCIS defined by RTOG 9804 criteria, no radiation was most cost-effective. The ICERs for IORT and WBRT, $152,753 and $208,204/QALY, respectively, exceeded the WTP threshold. IORT remained cost-effective in the setting of endocrine therapy use. Conclusion IORT was the most cost-effective radiation strategy for DCIS compared to WBRT and no radiation. This applied to all subgroups with the exception of low-risk DCIS defined by RTOG 9804 criteria for whom no radiation was the most cost-effective strategy. These findings provide support for ongoing studies examining the role of IORT for DCIS with high-risk features, as well as alternative treatment strategies for low-risk DCIS. Citation Format: Onishi M, Connolly EP, Wright JD, Vasan S, Gross T, Tsai W-Y, Chen L, Neugut AI, Accordino MK, Kalinsky K, Crew KD, Hershman DL. Cost-effectiveness analysis of intraoperative radiotherapy for ductal carcinoma in situ [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD7-03.