Percentage malignant involvement: a new concept in staging of breast cancer.

All the recognised systems of clinical staging of breast cancer have failed to provide reliable prognostic estimates of survival since they do not accurately reflect the pathological extent of the disease. In this prospective study of 52 female patients with established primary breast cancer we have measured the percentage neoplastic involvement of the breast at the time of mastectomy. This correlated well with the histological axillary node status, the subsequent development of overt metastatic disease, and survival during a follow-up period of 28-54 months.