1. A method of identifying a non-small cell lung cancer patient as being likely to benefit from treatment with a drug targeting an epidermal growth factor receptor pathway or not likely to benefit from treatment with said drug, comprising the steps of: a) obtaining a mass spectrum from a blood-based sample from the patient; b) performing one or more predefined pre-processing steps on the mass spectrum obtained in step a); c) obtaining integrated intensity values of selected features in said spectrum at one or more predefined m/z ranges after the pre-processing steps on the mass spectrum in step b) have been performed; d) using the values obtained in step c) in a classification algorithm using a training set comprising class-labeled spectra produced from blood-based samples from other patients to identify the patient as being either likely or not likely to benefit from the said drug.