Outcome of different radiotherapy strategies after breast conserving surgery in patients with ductal carcinoma in situ (DCIS)

• Published in: Acta oncologica 2023, Vol.62 (9), p.1-1051
• Main Authors: Wärnberg, Fredrik, Wadsten, Charlotta, Karakatsanis, Andreas, Olofsson Bagge, Roger, Holmberg, Erik, Lindman, Henrik, Sawyer, Elinor, Vicini, Frank, Mann, G Bruce, Karlsson, Per
• Format: Article
• Language: English
• Subjects: Cancer and Oncology; Cancer och onkologi; cost; DCIS; outcome; radiotherapy; recurrence
• ISSN: 0284-186X; 1651-226X; 1651-226X
• DOI: 10.1080/0284186X.2023.2245552

Adjuvant radiotherapy (RT) after breast-conserving surgery for DCIS lowers the relative local recurrence risk by half. To identify a low-risk group with the minimal benefit of RT could avoid side effects and spare costs. In this study, the outcome was compared for different RT-strategies using data from the randomized SweDCIS trial. Five strategies were compared in a Swedish setting: RT-to-none or all, RT to high-risk women defined by DCISionRT, modified Radiation Therapy Oncology Group (RTOG) 9804 criteria, and Swedish Guidelines. Ten-year recurrence risks and cost including adjuvant RT and local recurrence treatment cost were calculated. The mean age at recurrence was 64.4 years (36-90) and the mean cost for treating a recurrence was $21,104. In the SweDCIS cohort (  = 504), 59 women developed DCIS, and 31 invasive recurrence. Ten-year absolute local recurrence risk (invasive and DCIS) according to different strategies varied between 18.6% (12.5-23.6%) and 7.8% (5.0-12.6%) for RT-to-none or to-all, with an additional cost of $2614 US dollars per women and $24,201 per prevented recurrence for RT-to-all. The risk differences between other strategies were not statistically significant, but the larger proportion receiving RT, the fewer recurrences. DCISionRT spared 48% from RT with 8.1% less recurrences compared to RT-to-none, and a cost of $10,534 per prevented recurrence with additional cost depending on the price of the test. RTOG 9804 spared 39% from RT, with 9.7% less recurrences, $9525 per prevented recurrence and Swedish Guidelines spared 13% from RT, with 10.0% less recurrences, and $21,521 per prevented recurrence. It seems reasonable to omit RT in pre-specified low-risk groups with minimal effect on recurrence risk. Costs per prevented recurrence varied more than two-fold but which strategy that could be considered most cost-effective needs to be further evaluated, including the DCISionRT-test price.