SAN ANTONIO — Postmenopausal women with node-positive, estrogen-and/or progesterone-receptor-positive breast cancer have a 25% better long-term outcome with a postsurgical regimen of chemotherapy followed by tamoxifen than with adjuvant tamoxifen alone, Kathy S. Albain, M.D., said at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.
Ten-year results when chemotherapy and tamoxifen are given concurrently are significantly worse than with sequential therapy but better than with tamoxifen alone, added Dr. Albain, professor of medicine, hematology, and oncology and director of the breast cancer research program at Loyola University Chicago, Maywood, Ill.
She presented 10-year follow-up data from the Breast Cancer Intergroup of North America Trial 0100, in which 1,477 postmenopausal women with node-positive, endocrine-responsive disease were randomized to one of three postsurgical treatment regimens.
Ten-year disease-free survival was 48% in the tamoxifen arm; 53% in women who received concurrent cyclophosphamide, doxorubicin, 5-fluorouracil, and tamoxifen; and 60% in those who started on tamoxifen only after completing the triple-drug chemotherapy regimen.
The use of adjunctive chemotherapy in postmenopausal endocrine-responsive, node-positive disease has been controversial. But this study showed chemotherapy not only adds significant benefit to tamoxifen in terms of disease-free survival, but in overall survival as well, especially when given sequentially. The 10-year overall survival rate of women who received sequential chemotherapy followed by tamoxifen was 68%, compared with 62% with concurrent chemotherapy plus tamoxifen and 60% for tamoxifen alone.
A secondary purpose of the long-term analysis was to ascertain the value of tumor molecular biomarkers for prognosis as well as prediction of benefit from chemotherapy. Chemotherapy showed no benefit in the subset of patients whose tumor had a high estrogen-receptor score, had a low or intermediate nuclear grade, or was HER2 negative in the setting of one to three positive lymph nodes. In contrast, chemotherapy strongly enhanced disease-free survival in patients with low or intermediate levels of estrogen receptor in their tumor.