Neoadjuvant chemotherapy may help patients skip regional nodal irradiation

For patients whose breast cancer converted from lymph node-positive to lymph node-negative disease after neoadjuvant chemotherapy, skipping adjuvant regional nodal irradiation (RNI) did not increase the 5-year risk of disease recurrence or death, according to results from the NRG Oncology NSABP B-51/RTOG 1304 clinical trial.

For patients who undergo upfront surgery, the benefit of adjuvant RNI is well established in patients with pathologically positive axillary lymph nodes [1]. Patients who present with axillary node involvement, receive neoadjuvant chemotherapy, and are found to be pathologically node-negative at surgery have lower loco-regional recurrence rates compared with those who remain pathologically node-positive [2].

The phase 3 NSABP B-51/RTOG 1304 study (NCT01872975) evaluated the benefit of RNI in node-positive patients who are found to be node-negative (ypN0) after neoadjuvant chemotherapy. The study enrolled 1,641 patients with T1–3, N1, M0 breast cancer who converted to ypN0 after neoadjuvant chemotherapy and who had undergone either mastectomy or breast-conserving surgery. Participants were randomised 1:1 to RNI or no RNI. Participants in the no RNI arm who had breast-conserving surgery received whole breast irradiation. The primary outcome was invasive breast cancer recurrence-free interval (IBCRFI). Prof. Eleftherios Mamounas (Orlando Health Cancer Institute, FL, USA) presented the results [3].

After a median follow-up of 60 months, no difference in IBCRFI was observed between treatment arms (HR 0.88; 95% CI 0.60–1.29; P=051). Five-year estimates of IBCRFI were 91.8% and 92.7% for the no RNI and RNI arm, respectively. In addition, isolated loco-regional recurrence, distant recurrence, disease-free survival, and overall survival were not significantly different between the no-RNI and RNI arms.

Toxicities of grade 2–4 were more common in patients in the RNI arm. Radiation dermatitis of grade 3 occurred more with RNI (5.7% vs 3.3%).

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

1. McGale P, et al. Lancet. 2014;383:2127-2135.
2. Mamounas EP, et al. J Clin Oncol. 2012;30:3960-3966.
3. Mamounas EP, et al. 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, 5-9 December, San Antonio, TX, USA.

 

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Posted on 11 January 202411 January 2024