Abstract
While recognizing advanced tumours with endoscopy does not generally pose a challenge, cure rates are relatively low, depending on the size and stage of the tumour. Screening tests for cancer are advantageous for diagnosing cancers before the date after which a cure is no longer an option. Many gastrointestinal cancers are diagnosed after the date on which a cure is possible. The present article discusses some of the limitations of conventional white light endoscopy in screening and presents some of the fluorescent-based diagnostics that are being investigated as complements to white light endoscopy. Autofluorescence and fluorescence due to exogenous photosensitizers or precursors are two sources of fluorescence that are being studied. Preliminary results of current investigations are presented, and future research directions are described.