Multivariate Cox regression analysis of survival adjusted for the prognostic factors age, gender, tumour type (solid vs haematological), and baseline Hb level showed no change in the treatment effect estimates for epoetin beta (adjusted HRs ranging from 0.97 (95% CI 0.69, 1.36) to 1.00 (95% CI 0.71, 1.41). This evidence concerns the gene GSTM1 and neoplasm.