Effects of Chlorambucil and Therapeutic Decision in Initial Forms of Chronic Lymphocytic Leukemia (Stage A): Results of a Randomized Clinical Trial on 612 Patients

Abstract

In 1980, the French Cooperative Group on Chronic Lymphocytic Leukemia started a randomized clinical trial in which 612 good prognosis patients (stage A) received either no treatment (309 patients) or an indefinite course of chlorambucil at the daily dose of 0.1 mg/kg (303 patients). Overall survival appeared to be better in the untreated group (50 deceased patients compared with 62 in the chlorambucil group), but the difference was not significant (P = .21) even after adjusting for both prognostic and imbalanced factors (P = .09). The crude 5-year survival rates were 82% in the untreated group and 75% in the chlorambucil group. The action of chlorambucil appeared to be a complex phenomenon associating beneficial effects consisting in slowing down disease progression to stage B or C (P less than .01), and favoring disease remission with harmful effects given by a short survival after disease progression to stage B or C in the chlorambucil group and an increased incidence of epithelial cancers (33 v 19), as well as an excess of epithelial cancer deaths (13 v 3), in the chlorambucil group. As these results suggested an overall harmful effect of chlorambucil, we tried to define, within stage A patients, a group of patients with a low probability of disease progression. We showed that stage A patients with hemoglobin greater than or equal to 120 g/L and lymphocyte count less than 30 x 10(9)/L had a survival that was not significantly different (P = .46) from that of the age- and sex-matched French population. These patients, accounting for about 50% of all chronic lymphocytic leukemia patients, should not be treated unless disease progression is observed.