Survival advantage of adjuvant chemotherapy in high-risk node-negative breast cancer: ten-year analysis--an intergroup study

Abstract

Purpose: Preliminary analysis showed that adjuvant chemotherapy is effective in improving disease-free survival (DFS) among high-risk breast cancer patients. This report updates the analysis of the high-risk group and reports the results of the low-risk group.

Methods: Patients who had undergone a modified radical mastectomy or a total mastectomy with low-axillary sampling, with negative axillary nodes and either an estrogen receptor-negative (ER-) tumor of any size or an estrogen receptor-positive (ER+) tumor that measured > or = 3 cm (high-risk) were randomized to receive six cycles of cyclophosphamide, methotrexate, fluorouracil, and prednisone (CMFP) or no further treatment. Patients with ER+ tumors less than 3 cm (low-risk) were monitored without therapy.

Results: DFS and overall survival (OS) at 10 years were 73% and 81%, respectively, among patients who received chemotherapy, as compared with 58% and 71% in the observation group (P=.0006 for DFS and P=.02 for OS). Chemotherapy was beneficial for patients with large tumors, both ER+ and ER-, showing a 10-year DFS of 70% versus 51 % (P=.0009) and OS of 75% versus 65% (P=.06). Ten-year survival was 77% among low-risk patients, 85% among premenopausal patients, and 73% in the postmenopausal group.

Conclusion: The observed 37% reduction in risk of recurrence and 34% reduction in mortality risk at 10 years, associated with a 15.4% absolute benefit in disease-free state and 10.1% in survival, reaffirm the role of adjuvant chemohormonal therapy in the management of high-risk node-negative breast cancer. Tumor size remains a significant prognostic factor associated with recurrence and survival in the low-risk group.