Historical progress of the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual in patients with breast cancer.

Breast cancer is the most frequently diagnosed cancer and second leading cause of cancer death in countries around the world (1). Anatomic information, including information about the primary tumor (T), lymph node metastasis (N), and distant metastasis (M), has long been recognized to be indicative of cancer prognosis.