A single perioperative adjuvant chemotherapy course for node-negative breast cancer: five-year results of trial V. International Breast Cancer Study Group (formerly Ludwig Group).

Twelve hundred seventy-five patients who were defined as having node-negative breast cancer were evaluated in a randomized trial that compared a single cycle of combination chemotherapy started within 36 hours of surgery (848 patients) with no adjuvant treatment (427 patients). The chemotherapy consisted of intravenous cyclophosphamide, methotrexate, and fluorouracil given on days 1 and 8. Leucovorin (given on days 2 and 9) was added to the regimen to decrease severe toxic effects attributed to drug interaction between nitrous oxide used in anesthesia and methotrexate given in the immediate postoperative period. At a median follow-up of 60 months, the 5 year disease-free survival (DFS) percentages (+/- SE) were 74% +/- 2% for the treated group, and 68% +/- 2% for the no adjuvant therapy group. The estimated hazard ratio [95% confidence interval (CI)] was 0.78 (0.63 to 0.96); P = .02, representing a 22% +/- 9% relative reduction in the risk of relapse. The overall survival (OS) difference was not statistically significant with 5-year OS percentages of 88% +/- 1% for the treated group, and 85% +/- 2% for the control group [estimated hazard ratio (95% CI) = 0.85 (0.62 to 1.16); P = .31]. A subgroup analysis by menopausal status and by estrogen-receptor (ER) status revealed that the treatment effect was largest among the postmenopausal women with ER-negative tumors. The 5-year DFS percentages were 79% +/- 4% and 56% +/- 7%, and the OS percentages were 91% +/- 3% and 70% +/- 6%, for the treated and control groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)