Another method of determining breast cancer spread is to perform an endoscopic axillary sentinel node biopsy.

[citation needed] On CT scan or MRI, axillary lymphadenopathy can be defined as solid nodes measuring more than 1.5 cm without fatty hilum.

[5] Axillary lymph nodes are included within the standard tangential fields in radiotherapy for breast cancer.

In the case of comprehensive nodal irradiation, which includes axillary levels I, II, and III, as well as a supraclavicular lymph node field, there is a risk of damage to brachial plexus.

If brachial plexopathy does occur, it is generally a late effect and may not manifest itself until 10 or 15 years later, and usually presents with slight painless muscular atrophy.