Supraclavicular and infraclavicular lymph node delineation in breast cancer patients: a proposal deriving from a comparative study

Aims and background: Current advances in radiotherapy for breast cancer require knowledge of the anatomy of irradiated areas to minimize geographic miss and spare organs at risk. This study aimed at defining a contouring approach for supraclavicular (SC) and infraclavicular (IC) nodes after mastectomy or conservative surgery in patients with breast cancer. Methods and study design: In 15 patients, SC and IC nodes were contoured on computed tomography slices according to Madu et al and Dijkema et al. After analyzing relapse sites, as reported by Reed et al, our approach was defined. The 3 methods were compared in all patients, quantifying differences in contours by percentage overlap (PO). Results: In our approach, SC node delineation is similar to Madu et al in the ventral and medial landmarks, but includes the lateral SC nodes described by Dijkema et al. The lateral landmarks are the scalenus anterior and medius muscle lateral border and the clavicle. Dorsal boundaries are the scalenus anterior and medius muscle ventral and lateral surfaces and the subclavian artery ventral border. In IC node delineation, major differences emerged in cranial and dorsal limits which, in our approach, are the pectoralis minor muscle upper edge and the subclavian axillary artery ventral side. Our mean and median volumes and POs were between the other 2 methods. Conclusions: This study contributes to standardizing draining node contouring, so as to reduce variability and minimize geographic miss.