ADJUVANT CHEMOTHERAPY IN EARLY BREAST-CANCER AND INCIDENCE OF NEW PRIMARY MALIGNANCIES

Adjuvant chemotherapy is increasingly being given to patients with early breast cancer. Long-term follow-up studies suggest a higher frequency of secondary tumours, especially leukaemias, among women receiving such cytotoxic drugs. We studied the frequency of new primary malignancies in 1113 patients with early breast cancer who had been included in a randomised trial to compare chemotherapy as an adjunct to primary surgery with adjuvant locoregional radiotherapy. The estimated rate of new primary malignancies at ten years was significantly lower (p < 0.0003) in the chemotherapy group (1%) than in the radiotherapy group (6%). The corresponding rate among 1986 patients treated with surgery alone was 5%. Our findings suggest that adjuvant chemotherapy in early breast cancer may protect against the development of new primary tumours in the first ten years of follow-up.