Pathologic response to induction chemotherapy in locally advanced carcinoma of the breast: a determinant of outcome.

The prognosis for patients with locally advanced carcinoma of the breast remains poor. This study examines the pathologic evidence of response of the mammary tumor and axillary nodes after preoperative chemotherapy. We sought to determine if there was a relationship between the histologic response and clinical outcome. Between 1987 and 1992, 36 patients with locally advanced carcinoma of the breast received three cycles of chemotherapy after incisional biopsy. Modified radical mastectomy was then performed. The breast and axillary nodes were examined pathologically for therapeutic effect and a grading scale was assigned. Postoperatively, patients received completion chemotherapy with the same agents used preoperatively followed by radiation therapy to the chest wall. Fourteen tumors (39 percent) showed near total therapeutic effect, five (14 percent) showed greater than 50 percent but less than total effect, 12 (33 percent) showed less than 50 percent effect, and five (14 percent) showed no effect. Nodal positivity was seen in 61 percent of the patients. Overall clinical response to induction chemotherapy was seen in 86 percent of the patients. There was poor correlation between clinical and pathologic response. Only 50 percent of the patients with complete clinical response were pathologically free of disease. Patients with excellent pathologic therapeutic response had a 79 percent overall five-year survival rate compared with 34 percent for tumors with a lesser response. This was irrespective of nodal status. While pathologic response was critical in determining outcome, clinical response was not. These results indicate that patients whose tumors have the best pathologic response to induction chemotherapy experience the best outcome.