The present invention relates to prognostic methods which are useful in medicine, particularly cancer chemotherapy. The object of the invention to provide a method for assessing GST-pi expression levels in fixed or fixed and paraffin embedded tissues and prognosticate the probable resistance or sensitivity of a patient's tumor to treatment with platinum-based therapies by examination of the amount of GST-pi mRNA in a patient's tumor cells and comparing it to a predetermined threshold expression level. More specifically, the invention provides to oligonucleotide primer pair GST-piand methods comprising their use for detecting levels of GST-pi mRNA.