Use of internal mammary and medial supraclavicular (IM-MS) irradiation in women with stage I to III breast cancer resulted in a significant reduction in breast cancer mortality and any breast cancer recurrence, according to the 15-year results of the EORTC 22922/10925 trial.1 However, no improvement in overall survival was seen.
The trial randomly assigned 4004 patients aged up to 75 years with unilateral, stage I to III breast adenocarcinoma with involved axillary nodes or a central or medially located primary tumor to treatment with or without IM-MS irradiation. Irradiation was given at 50 Gy in 25 fractions.
“After a follow-up of about 10 years, our study showed that regional nodal irradiation improved overall disease-free survival, distant disease-free survival, and breast cancer mortality,” the researchers wrote.
With a median follow-up of longer than 15 years, 27.7% of patients in the IM-MS irradiation group had died compared with 28.4% of patients in the control group. Overall survival was similar between the 2 groups (73.1% vs 70.9%; hazard ratio [HR}, 0.95; 95% CI, 0.84-1.06; P =.36). Additionally, there was no significant difference in disease-free survival or distant metastasis-free survival between the groups.
However, patients assigned to IM-MS irradiation did have improved breast cancer recurrence (24.5% vs 27.1%; HR, 0.87; 95% CI, 0.77-0.98; P =.024) and breast cancer mortality (16% vs 19.8%; HR, 0.81; 95% CI, 0.70-0.94; P =.0055).
“We could not clearly identify a patient subgroup that benefits most from elective nodal
irradiation, based on combinations of patient-related, tumour-related, and other treatment-related factors,” the researchers wrote. “Our results together with those of others support selective use of nodal irradiation for patients at high risk of recurrence.”
Poortmans PM, Weltens C, Fortpied C, et al. Internal mammary and medial supraclavicular lymph node chain irradiation in stage I-III breast cancer (EORTC 22922/10925): 15-year results of a randomized, phase 3 trial. Lancet Oncol.Published online November 2, 2020. doi:10.1016/S1470-2045(20)30472-1