Abstract: Disclosed is a method of diagnosing cancer in a subject, comprising determining a level of one or more volatile organic compounds for cancer in a urine sample obtained from the subject, wherein the identity and/or the level of the biomarker is determined by a mass spectrometry method, such as gas chromatography-mass spectrometry or tandem mass spectrometry. Specific biomarkers identified using the method and the use of the method to identify subjects as requiring treatment for cancers are also disclosed.