The omission of adjuvant regional nodal irradiation did not appear to increase the risk for recurrence or death among patients with breast cancer whose disease converted from lymph node-positive to lymph node-negative after neoadjuvant chemotherapy, according to research presented at the 2023 San Antonio Breast Cancer Symposium. 

There is no standard of care in place for patients with breast cancer for whom neoadjuvant chemotherapy has eliminated lymph node involvement, the researchers explained.  

The researchers performed a phase 3 clinical trial of 1,641 patients with lymph-node positive, nonmetastatic breast cancer who were found to have no lymph node involvement after neoadjuvant chemotherapy and surgery. They randomly assigned patients to two different regimens.  

One group was assigned to skip regional nodal irradiation after undergoing mastectomy or whole breast irradiation and breast-conserving surgery. The other group was assigned to continue with chest wall irradiation and regional nodal irradiation following mastectomy or whole-breast irradiation plus regional nodal irradiation and breast-conserving surgery. 

Median follow-up was 59.5 months, and patients were a median of 52 years old. Seventy-eight percent had experienced a complete breast pathological response. 

In the “no regional nodal irradiation group,” 91.8% of patients were invasive breast cancer-recurrence free at 5 years compared with 92.7% of those who did undergo regional nodal irradiation. In both groups, 93.4% of patients were reported to be distant-recurrence free at 5 years.  

Overall survival was 94% in patients who were assigned to skip regional nodal irradiation and 93.6% in those who did not skip the therapy, according to the researchers. 

The researchers are planning a longer-term follow-up to further examine their findings, and a 10-year analysis time point was reached this past year. 

“Our findings suggest that downstaging cancer-positive regional lymph nodes with neoadjuvant chemotherapy can allow some patients to skip adjuvant regional nodal irradiation without adversely affecting oncologic outcomes. Follow-up of patients for long-term outcomes continues,”  

- Eleftherios Mamounas, MD, professor of surgery at the University of Central Florida and medical director of the Comprehensive Breast Program at the Orlando Health Cancer Institute. 

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Reference: 

Mamounas, E. Loco-regional irradiation in patients with biopsy-proven axillary node involvement at presentation who become pathologically node-negative after neoadjuvant chemotherapy: Primary outcomes of NRG Oncology/NSABP B-51/RTOG 1304. Abstract GS02-07. SABCS 2023. 

Disclosures: Mamounas declared financial ties to drug makers. The study was supported by the National Institutes of Health. 

By Andrew John, MD /alert Contributor

Photo Credit: Getty Images.