Secondary leukemia after epirubicin-based adjuvant chemotherapy in operable breast cancer patients: 16 years experience of the French Adjuvant Study Group.

ABSTRACT

BACKGROUND: The purpose of this study was to evaluate incidence and risk factors of secondary leukemia after adjuvant epirubicin-based chemotherapy in breast cancer patients. PATIENTS AND METHODS: Among eight French Adjuvant Study Group trials, 3653 patients were assessable 2603 received epirubicin; 682 received hormonotherapy; and 368 had no systemic treatment. Chemotherapy was FEC regimen in 85% of cases (fluorouracil 500 mg/m2, epirubicin 50, 75 or 100 mg/m2, cyclophosphamide 500 mg/m2, three or six cycles). Epirubicin cumulative dose was <300 mg/m2 in 1045 patients; 300-600 mg/m2 in 1187; and > or =600 mg/m2 in 286, followed by radiotherapy in 96% of cases. The median follow-up was 104 months. RESULTS: Eight cases of leukemia occurred in epirubicin-exposed patients and one in non-exposed patients. After 9 years, the risk of developing a leukemia was 0.34% (95% confidence interval 0.11-0.57) in epirubicin-exposed patients. In patients receiving chemotherapy, leukemia subtypes were AML2 (two), AML3 (one), AML4 (three) and ALL (two). None of the classically recognized risk factors was significantly correlated with the occurrence of a leukemia. CONCLUSION: Irrespective of the dose, the incidence of secondary leukemia after adjuvant epirubicin-based chemotherapy was low. After a long follow-up, the benefit/risk ratio for early breast cancer patients remained in favor of epirubicin-based adjuvant chemotherapy eight cases (0.31%) occurred, and in some of them, treatment causality could be debatable.