Abstract: Non-invasive methods of detecting and providing an early diagnosis of cancer, in particular breast cancer are provided herein. The methods include obtaining a sample, suitably an ocular wash sample, from a subject and determining the level of ?-Defensin 1, ?-Defensin 2 and/or ?-Defensin 3 in the sample. Increased levels of any of these proteins as compared to a negative control or non-cancerous subject are indicative of cancer in the subject from which the sample was obtained. Kits for performing the methods described herein are also provided.