METHODS: The realization of the new guidelines was a step by step process that started with multiple expert meetings where the existing guidelines were analyzed and the delineations of the lymph node regions were performed together with a surgeon, specialized in the anatomy of the drainage of the breast.
RESULTS: The delineation guidelines are vessel-based. Since the occurrence of pathological lymph nodes is typically around the veins, the cranial and caudal borders of all different nodal regions are based on a 5mm margin around the veins, except for the parasternal lymph node area. Compared to the existing guidelines there are some major changes.
CONCLUSIONS: With this project a national as well as a European (ESTRO) consensus guideline for the delineation of the regional lymph node areas in breast RT is reached. The new delineation atlas is vessel-based and no longer field-based.