<p>The present invention relates to a method for classifying a tissue biopsy sample obtained from a tumour, comprising determining a plurality of stiffness values for said sample by measuring a plurality of points on the sample with a spatial resolution of at least 100 µm and assigning the sample to a probability of malignancy. A sample showing a unimodal stiffness distribution is assigned to a high probability of being non-malignant, and a sample showing an at least bimodal stiffness distribution is assigned to a high probability of being malignant, wherein said stiffness distribution is characterized by a first peak exhibiting an at least two fold higher stiffness value than a second peak. The present invention further relates to a system for classifying a tumour tissue biopsy sample.</p>