Treating Non–Low-Risk Ductal Carcinoma In Situ With Tumor Bed Boost After Whole-Breast Irradiation

By: Joseph Fanelli
Posted: Tuesday, December 6, 2022

According to findings presented in The Lancet, for patients with resected non–low-risk ductal carcinoma in situ, a tumor bed boost following whole-breast irradiation may reduce local recurrence, although with an increase in grade 2 or higher toxicities. Boon H. Chua, MBBS, PhD, of the Nelune Comprehensive Cancer Center, Randwick, Australia, and colleagues concluded that moderately hypofractionated whole-breast irradiation may prove to be as safe and effective as conventional whole-breast irradiation. The investigators believe the international scale of the study may support the generalizability of their findings.

In this phase III trial (BIG 3-07/TROG 07.01), the authors enrolled 1,608 patients from six participating centers across the globe. Eligible patients were women with unilateral, histologically proven, non–low-risk ductal carcinoma in situ who were treated with breast-conserving surgery with at least 1 mm of clear radial resection margins. Of the group, 805 patients did not receive a tumor bed boost, and 803 did. Conventional whole-breast irradiation was given to 831 patients, and 777 patients received hypofractionated whole-breast irradiation.

After a median follow-up of 6.6 years, the 5-year free-from-local-recurrence rate was 92.7% for patients who did not receive a tumor bed boost and 97.1% for patients who did. The authors reported there was no statistically significant difference in the 5-year free-from-disease-recurrence rate when comparing patients who received conventional whole-breast irradiation (90.0%) and hypofractionated therapy (92.4%). There was also no statistical difference observed when comparing the 5-year overall survival rate for those who received a tumor bed boost (98.2%) and those who did not (99.0%).

Those who received a boost also had higher rates of grade 2 or higher breast pain (10%) than those who did not. In addition, higher rates of induration (6%) were reported with the tumor bed boost than without it (14%).

Disclosure: For full disclosures of the study authors, visit thelancet.com.

The Lancet