For most women with early stage breast cancer, researchers have found that a single dose of targeted radiotherapy during surgery is just as effective as conventional radiotherapy, which typically requires several hospital visits after surgery.

This approach, called targeted intraoperative radiotherapy (IORT), is restricted only to the area around the tumor and is given immediately following surgery. Conventional radiotherapy approaches involve doses to the entire breast over several days.

According to the study findings, IORT is associated with an approximately 80% chance of avoiding a full course of conventional radiotherapy, fewer adverse effects, and no difference in survival or the likelihood of the cancer returning.

Earlier reports investigating single dose targeted IORT showed promising results, but physicians wanted more long-term results before widely adopting the procedure. The new findings are based on a study of 2298 women ages 45 and older who were eligible for lumpectomy.

Between March 2000 and June 2012, 1140 participants received targeted IORT and 1158 received external beam radiotherapy (EBRT). IORT was administered after surgery as part of the same operation and under the same anesthetic, whereas EBRT was given as a standard daily dose for 3 to 6 weeks after surgery.

The long-term study results found that IORT was no worse than EBRT. After 5 years of monitoring, the local recurrence risk was 2.11% for IORT compared with 0.95% for EBRT, which the authors said is not a clinically significant difference. In the first 5 years after surgery, there were 13 additional local recurrences but 14 fewer deaths in the IORT cohort compared with the EBRT cohort.

Over a longer follow-up period, with an average of 8.6 years and a maximum of 18.9 years, there were no statistically significant differences in local recurrence-free survival, mastectomy-free survival, overall survival, and breast cancer deaths. Deaths from other causes were also significantly lower with IORT compared with EBRT, and the major risk factors for such deaths were well matched between the groups.

Based on these findings, the authors wrote that for many patients with early breast cancer, “risk adapted immediate single-dose IORT during lumpectomy is an effective alternative to EBRT, with comparable long-term efficacy for cancer control, and lower non-breast-cancer mortality.”

REFERENCE
Single dose radiotherapy as good as conventional radiotherapy for most women with early breast cancer [news release]. BMJ; August 19, 2020. https://www.bmj.com/company/newsroom/single-dose-radiotherapy-as-good-as-conventional-radiotherapy-for-most-women-with-early-breast-cancer/. Accessed October 8, 2020.