Method for determining whether a mammalian subject having a cancer belongs to a first or a second group, wherein subjects of the first group are more likely to respond to a platinum-based therapy than subjects of the second group, comprising the steps of: evaluating the amount of RBM3 protein or RBM3 mRNA present in at least part of a sample earlier obtained from said subject, and determining a sample value corresponding to said amount; comparing the sample value with a reference value; and, if said sample value is higher than said reference value, concluding that said subject belongs to a first group; and if said sample value is lower than or equal to said reference value, concluding that said subject belongs to a second group. There is further provided means useful in the establishment of a treatment prediction.