Abstract: Described herein are methods of immunoassay for detecting and/or monitoring cancer in a patient. A sample from the patient is contacted with denatured type III collagen. The amount of binding between the denatured type III collagen and antibodies in the sample that specifically recognise and bind to denatured type III collagen is then detected and determined, and the amount of binding is correlated with values associated with normal healthy subjects, and/or with values associated with known disease severity, and/or with values obtained from the patient at a previous time point, and/or with a predetermined cut-off value.