What guides regional nodal irradiation in node positive breast cancer following upfront sentinel lymph node biopsy?

This study aimed to evaluate decision-making patterns among international experts regarding breast cancer regional node irradiation (RNI), using an objective, consensus-driven approach.

Twenty-one international radiation oncology experts were invited to participate in a consensus-based evaluation of RNI recommendations. Participants provided responses to clinical scenarios involving early-stage breast (cN0) cancer with sentinel lymph node biopsy (SNLB)-positive findings (pN1a) without completion axillary lymph node dissection (ALND). Decision-making parameters, including patient age, tumour characteristics, and biological risk factors were analysed.

Of the 21 experts, 19 completed the evaluation. Responses included 22 different decision-making criteria and demonstrated considerable variability in decision-making, even after simplifying treatment options. Consensus was most frequently observed in high- and low-risk cases, with comprehensive RNI or omission of RNI being recommended, respectively. However, for intermediate-risk scenarios, no clear agreement was reached reflecting different clinical considerations and assessment of risk factors.

Due to many randomised studies investigating different risk factors that do not always coincide, breast cancer experts rely on a wide variety of criteria to recommend RNI for pN1(sn) breast cancer, leading to heterogeneity in decision-making. With this work we aim to raise awareness of this challenge to provoke revision of current guidelines and expert-based recommendations.