Staging is a way to classify how advanced a breast cancer is, which indicates a patient’s prognosis.

The three basic measures a pathologist uses to stage cancer are TNM, or tumor size, lymph node status, and metastasis (cancer that has spread to other parts of the body). Currently, pathologists also consider biological information including tumor grade, hormone receptor status, and Her2 status. This process of staging occurs twice, both before and after surgery.