The International (Ludwig) Breast Cancer Study Group Trials I-IV: 15 years follow-up.

BACKGROUND: Adjuvant systemic therapy prolongs disease-free and overall survival in both pre- and postmenopausal patients. Available data shown benefit from multi-agent chemotherapy, prolonged tamoxifen treatment, and ovarian ablation, and that the combination of chemo- and endocrine therapy might be advantageous. In 1978 the International (Ludwig) Breast Cancer Study Group (IBCSG) initiated four complementary randomized controlled clinical trials to evaluate the roles of chemo-endocrine combinations or endocrine therapy alone in specific populations defined by risk (for pre- and perimenopausal patients) or by age (for postmenopausal patients). The results at 10 and 13 years' median follow-up for these trials are summarized in this report and are compared to those of the Overview meta-analysis with regard to chemo-endocrine or endocrine therapy combinations. Furthermore, types of first relapses by sites and second malignant diseases are reported.

PATIENTS AND METHODS: 1601 evaluable patients with node positive disease were included into the studies I-IV. In Trial I (491 premenopausal patients with 1-3 positive axillary nodes) we studied the addition of low-dose continuous prednisone (p) to a cyclophosphamide-methotrexate-fluorouracil (CMF) combination. In Trial II 327 premenopausal patients with four or more positive axillary nodes were randomized to one year CMFp or to a surgical oophorectomy followed by CMFp. In Trial III (463 postmenopausal patients 65 years old or younger), combined chemoendocrine therapy (one year of CMFp plus tamoxifen (T)) was compared to endocrine therapy (1 year of p + T) or to surgery alone. In Trial IV 320 postmenopausal patients 66 to 80 years old were treated either by surgery alone or by surgery followed by 1 year prednisone and tamoxifen.

RESULTS: In Trial I the addition of prednisone allowed a higher dose of cytotoxics to be administered compared with CMF alone. Despite this increased dose intensity, 13-year disease-free survival (DFS) and overall survival (OS) were similar for the two treatment groups (49% vs. 52% DFS, 59% vs. 65% OS for CMFp vs. CMF). In Trial II the addition of surgical oophorectomy to CMFp yielded an improved outcome which approached statistical significance for the subset of 107 patients known to have estrogen receptor-positive tumors (DFS, 23% vs. 15%, p = 0.13; OS, 41% vs. 30%, p = 0.12). In Trial III combined chemoendocrine therapy improved DFS and OS compared with endocrine therapy alone (p + T) given for the same duration, or no adjuvant treatment (DFS, 35% vs. 25% vs. 14%, p < 0.0001; OS, 48% vs. 36% vs. 32%, p = 0.01). In Trial IV p + T improved DFS compared with no adjuvant therapy (27% vs. 15%, p = 0.004). Despite competing risks for this elderly population, OS was also improved but the result was not statistically significant (34% vs. 22%, p = 0.08).

CONCLUSIONS: The overall results of these four trials indicate that the continuation of investigations on combined chemo-endocrine therapies is warranted. The prognosis of the patients, all node-positive, treated with the most effective adjuvant treatment is such that there is a large potential for improvement.