MONDAY, March 30, 2026 (HealthDay News) -- De-escalation of locoregional radiotherapy (RT) based on ypN-status seems safe for patients after primary systemic treatment (PST) for breast cancer, according to a study presented at the annual European Breast Cancer Conference, held from March 25 to 27 in Barcelona, Spain.
Fleur Mauritz, M.D., from the Maastricht University Medical Center in the Netherlands, and colleagues examined the long-term safety of tailoring locoregional RT to the nodal response after PST for locoregional recurrence rate (LRR), recurrence-free interval (RFI), and overall survival (OS) in 848 patients. Participants were treated with PST followed by lumpectomy or mastectomy combined with sentinel lymph node biopsy and/or marked axillary lymph node removal or axillary lymph node dissection (ALND). Based on ypN-status, three risk groups were defined: low-risk (ypN0); intermediate-risk (ypN1); and high-risk (ypN2+). Radiation was tailored accordingly: whole breast RT (WBRT) after lumpectomy or no RT after mastectomy for the low-risk group; WBRT or chest wall RT and RT of axillary levels 1 to 2 in the case of no ALND for the intermediate-risk group; and WBRT or chest wall RT and RT of the nonresected part of the axilla with/without internal mammary nodes RT for the high-risk group.
Eight hundred thirty-eight patients completed follow-up. The researchers found that for the total cohort, the 10-year LRR was 2.9 percent, while for low-, intermediate-, and high-risk groups, the LRR was 2.4, 3.2, and 2.8 percent, respectively. The 10-year RFI and OS were 79.2 and 83.0 percent, respectively, with significant differences seen between risk groups (RFI: 88.2, 78.9, and 64.9 percent for low-, intermediate-, and high-risk groups, respectively; OS: 90.7, 83.0, and 70.5 percent, respectively).
"Tailoring the extent of radiotherapy according to how well the chemotherapy has worked to treat cancer in the lymph nodes, leads to very low and reassuring recurrence rates in the breast and surrounding area," Mauritz said in a statement.