The present disclosure relates, in one of its aspects, to a method for determining whether a mammalian subject having a bladder cancer belongs to a first or a second group, wherein the prognosis of subjects of the first group is better than the prognosis of subjects of the second group. The method comprises the steps of: a) evaluating an amount of RBM3 in at least part of a sample earlier obtained from the subject and determining a sample value corresponding to the evaluated amount; b) comparing said sample value with a predetermined reference value; and if said sample value is higher than said reference value, c1) concluding that the subject belongs to the first group; and if said sample value is lower than or equal to said reference value, c2) concluding that the subject belongs to the second group.