Table 1.

RTOG regional nodal contours: anatomic boundaries

Axilla level	Cranial	Caudal	Anterior	Posterior	Lateral	Medial
I	Axillary vessels cross lateral edge of pectoralis minor muscle m.	Pectoralis major muscle inserts into ribs	Plane defined by anterior surface of pectoralis major m. and latissimus dorsi m.	Anterior surface of subscapularis m.	Medial border of latissimus dorsi m.	Lateral border of pectoralis minor m.
II	Axillary vessels cross medial edge of pectoralis minor m.	Axillary vessels cross lateral edge of pectoralis minor m.	Anterior surface pectoralis minor m.	Ribs and intercostal muscles	Lateral border of pectoralis minor m.	Medial border of pectoralis minor m.
III	Pectoralis minor m. insert on coracoid process	Axillary vessels cross medial edge of pectoralis minor m.	Posterior surface pectoralis major m.	Ribs and intercostal muscles	Medial border of pectoralis minor m.	Thoracic inlet

Abbreviation: RTOG = Radiation Therapy Oncology Group.