ASTRO 2018: Radiation After Surgery for Low-Risk Ductal Carcinoma in Situ
Posted: Friday, November 9, 2018
Radiation therapy following surgery for women with low-risk ductal carcinoma in situ reduced the rate of local tumor recurrence in the long term. Results from the 12-year update of the NRG/RTOG 9804 trial showed that although the risk of tumor recurrence was low overall, radiation therapy lowered it even more. Beryl McCormick, MD, of Memorial Sloan Kettering Cancer Center, New York, presented the updated findings at the 2018 Annual Meeting of the American Society for Radiation Oncology (ASTRO) in San Antonio (Abstract LBA1).
“Radiation reduced recurrence by more than 70%, and this was a much more profound impact than we expected,” commented Dr. McCormick in an ASTRO press release.
In the long-term analysis of this phase III trial, local tumor recurrence was assessed in 629 patients with low-risk ductal carcinoma in situ, 75% of whom were postmenopausal. Patients were randomly assigned to receive whole-breast radiation therapy or observation alone after breast-conservation surgery. All patients had the option of tamoxifen treatment for 5 years.
The cumulative incidence of local recurrence was 2.8% for patients who had received radiation therapy compared with 11.4% for those who had received observation alone. The 12-year cumulative incidence of invasive local recurrence was 1.5% versus 5.8%, respectively. In multivariate analysis, patients who had received radiation therapy and tamoxifen alone experienced reduced local tumor recurrence. No differences in overall survival, disease-free survival, or rates of mastectomy were found.
“All of us have a different definition of what is an acceptable risk,” concluded Dr. McCormick. “Some patients with [ductal carcinoma in situ] will still want radiation therapy. But for others, the risk is so low they may opt not to treat, and that should be considered a viable option.”
