Table 1 Anatomic boundaries of the ipsilateral breast and axillary lymph node Levels I-III as defined by the Radiation Therapy Oncology Group (RTOG) contouring atlas [1]
Cranial | Caudal | Medial | Lateral | Anterior | Posterior | |
|---|---|---|---|---|---|---|
Breast | Clinical reference and second rib insertion | Clinical reference and loss of CT apparent breast | Sternal-rib junction | Clinical reference and mid axillary line. Excludes latissimus dorsi | Skin | Excludes pectoralis muscles, chestwall muscles, ribs |
Level I | Axillary vessels crossing lateral edge of pectoralis minor | Pectoralis major insertion into ribs | Axillary vessels crossing lateral edge of pectoralis minor | Medial border of latissimus dorsi | Plane defined by the anterior surface of pectoralis major and latissimus dorsi | Anterior surface of subscapularis |
Level II | Axillary vessels crossing medial edge of pectoralis minor | Axillary vessels crossing lateral edge of pectoralis minor | Medial border of pectoralis minor | Lateral border of pectoralis minor | Anterior surface of pectoralis minor | Ribs and intercostal muscles |
Level III | Pectoralis minor insertion on corocoid process | Axillary vessels crossing medial edge of pectoralis minor | Thoracic inlet | Medial border of pectoralis minor | Posterior surface of pectoralis major | Ribs and intercostal muscles |