Purpose: Late abnormalities of left ventricular (LV) performance occur in most survivors of childhood acute lymphoblastic leukemia (ALL) treated with moderate anthracycline doses. We studied the prevalence of late cardiotoxicity in patients treated with lower anthracycline doses and related this to survival.
Patients and methods: Echocardiograms were performed in 50 normal children and 120 relapse-free ALL survivors 6.2 +/- 2.0 years after the end of cumulative daunorubicin doses of 90 mg/m2 (n = 40), 180 mg/m2 (n = 40), or 270 mg/m2 (n = 40) on UKALL X pilot (1982 to 1984) or UKALL X (1985 to 1989) protocols. Age at treatment onset was 4.7 +/- 2.8 years. Cardiac abnormalities were reviewed in light of the UKALL X 5-year disease-free survival rates of 57% (95% confidence interval [CI], 51% to 63%), 61% to 62% (95% CI, 56% to 68%), and 71% (95% CI, 66% to 76%) for the groups that received 90, 180, and 270 mg/m2 of daunorubicin, respectively.
Results: ALL survivors had reduced LV fractional shortening (FS) compared with normal (32.3% +/- 4.4% v 35.9% +/- 4.2%, P < .005), which was accounted for by increased LV end-systolic stress (49.4 +/- 13.5 v 42.2 +/- 9.1 g/cm2, P < .001), whereas LV contractility independent of loading conditions was normal for the group as a whole. Of 27 patients (23%) with cardiac abnormalities, 25 (21%) had increased end-systolic stress, whereas only two (2%) had reduced contractility. The proportion with cardiac abnormality was similar in the three dose groups. Anthracycline dose, age at treatment, sex, follow-up duration, growth hormone, pubertal status, hemoglobin level, and total WBC count at presentation were not predictive of increased LV end-systolic stress.
Conclusion: There was a reduced incidence and severity of cardiac abnormalities with the lower anthracycline dose protocols (90 to 270 mg/m2) studied compared with previous reports in which subjects had received moderate anthracycline doses (approximately 300 to 550 mg/m2). Cumulative anthracycline dose within the range 90 to 270 mg/m2 did not relate to cardiac abnormalities. This suggests that there may be no safe anthracycline dose to avoid late cardiotoxicity, but reinforces the use of the protocol that affords best survival within the dose range studied.