Phase III trial of concurrent or sequential adjuvant chemoradiotherapy after conservative surgery for early-stage breast cancer: final results of the ARCOSEIN trial.

PURPOSE: In 1996, we initiated the French multicenter phase III randomized trial to compare the effect on disease-free survival (DFS) of concurrent versus sequential chemotherapy (CT) and radiotherapy (RT) after breast-conserving surgery for stages I and II breast cancer. This report presents the clinical results with a median follow-up of 60 months.

PATIENTS AND METHODS: Between February 1996 and April 2000, 716 patients were entered onto this trial. Adjuvant treatment began within 6 weeks after surgery. Sequential treatment of CT administered first followed by RT was compared with concurrent treatment of CT administered with RT. The CT regimen consisted of mitoxantrone (12 mg/m2), fluorouracil (500 mg/m2), and cyclophosphamide (500 mg/m2) on day 1, and it was repeated every 21 days for six courses. RT was delivered to the breast and, when indicated, to the regional lymphatics.

RESULTS: There was no statistically significant difference in treatment in the 5-year DFS (80% in both groups; P = .83), locoregional recurrence-free survival (LRFS; 92% in sequential v 95% in concurrent; P = .76), metastasis-free survival (87% in sequential v 84% in concurrent; P = .55), or overall survival (90% in sequential v 91% in concurrent; P = .76). Nevertheless, in the node-positive subgroup, the 5-year LRFS was statistically better in the concurrent arm (97% in concurrent v 91% in sequential; P = .02), corresponding to a risk of locoregional recurrence decreased by 39% (hazard ratio, 0.61; 95% CI, 0.38 to 0.93).

CONCLUSION: This treatment protocol remains an appealing clinical option for many women with operable breast cancer at a high risk of recurrence. Combination treatments with new drugs for breast cancer are warranted.