Patient selection in high-dose chemotherapy trials: relevance in high-risk breast cancer

To evaluate the impact of the selection criteria that are used in current high-dose consolidation chemotherapy (HDCT) trials on the outcome of high-risk breast cancer patients treated with conventional adjuvant chemotherapy.

From 1975 to 1995, 265 breast cancer patients at our institution showed involvement of ten or more positive axillary lymph nodes. Of these, 171 received standard adjuvant combination chemotherapy, but not HDCT consolidation, and were the subjects of our study. One hundred twenty-eight patients met the standard selection criteria for HDCT with hematological support (< 60 years, no significant concomitant disease, and no progression during adjuvant treatment), whereas 43 did not. Clinical outcome was analyzed by using disease-free survival (DFS) and overall survival (OS) as endpoints. To provide an assessment of the short-term efficacy of HDCT, we also evaluated the outcome in a cohort of 39 patients from the last 4 years who met the criteria for, and were actually treated with, HDCT after adjuvant chemotherapy.

With a median follow-up of 4.4 years (range, 0.7 to 17.2 years), 112 of the 171 patients have had a relapse, and 87 have died. The estimated 5-year DFS was 32.3%, and OS was 49.4%. DFS was significantly higher for patients who met the HDCT criteria (36.6% at 5 years) than for those who did not (15.8% at 5 years; P < .05). OS was also significantly more favorable in patients meeting HDCT criteria (55.4% at 5 years) than in patients not meeting HDCT criteria (22.7% at 5 years; P < .01). We performed a multivariate analysis to adjust for other potential prognostic factors and found that meeting the HDCT criteria and having undergone locoregional radiotherapy were the only significant independent predictors for DFS and OS. Finally, we compared the outcome of the 128 patients who met the HDCT criteria and were treated with conventional adjuvant chemotherapy only with that of the 39 patients who met the criteria and who actually underwent HDCT, and we did not observe significant differences in the DFS or OS between these groups.

Meeting HDCT inclusion criteria is an independent indicator of favorable prognosis in high-risk breast cancer patients. The selection of patients by these criteria may explain, at least in part, the promising short-term results of nonrandomized adjuvant HDCT trials in high-risk breast cancer.