All breast cancer patients presenting preoperatively at the Dr. W.W. Cross Cancer Institute, Edmonton, since 1971 are included in a registry that provides detailed clinical and epidemiologic information on the nature of this disease in northern Alberta. For the 141 female patients who were seen preoperatively in 1971 and thereafter followed regularly, disease was restaged according to the 1973 revision of the tumour-nodes-metastases (TNM) formula of Union internationale contre le cancer (UICC) to permit comparison with staging according to the 1968 formula. The staging distribution was altered greatly because of major changes in the staging system. With the 1973 revision stage II includes disease without palpable lymph nodes and greater emphasis is placed on tumour size. Accurate preoperative staging and registration are essential for meaningful statistics and as an aid in patient management.