Relationship among outcome, stage of disease, and histologic grade for 22,616 cases of breast cancer. The basis for a prognostic index.

Survival rates for 22,616 cases of breast cancer listed in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute were stratified on outcome according to the histologic grade and stage of disease. Two different staging systems, "local, regional, and distant" and a modified American Joint Committee on Cancer (AJCC) system adopted for SEER were used. Relative survival rates were calculated at 5 and 10 years. Patients who were assigned Stage II, Grade 1 had the same survival as those assigned Stage I, Grade 3. Their survival was better than patients assigned Stage I, Grade 4. The 5-year relative survival rate for patients listed as Stage I, Grade 1 was 99% and for patients listed as Stage I, Grade 2, it was 98%. At 10 years, the survival rate of patients assigned Stage I, Grade 1 was 95%. Patients with histologic Grade 1 tumors less than 2 cm in size and with positive axillary lymph nodes had a 5-year survival rate of 99%. As breast tumors increased in size, the histologic grade also increased. The results suggest that in linking histologic grade with stage of disease, the staging system should also be considered. Histologic grade when used in conjunction with stage of disease can improve the prediction of outcome. Our results also indicate that a prognostic index can be created for breast cancer using a combination of stage of disease and histologic grade. The data suggest that only three grades are needed for breast cancer.