Retinoic acids in oral precancer: Utility and challenges

Introduction: Oral cancer is leading cause of mortality & morbidity in both developing and developed world. It is often preceded by precancer which can be identified visually. Early intervention can substantially reduce progression to frank cancer. Several chemoprevention strategies have been tested of which Retinoid Acid is one. Retinoid Acid has important functions in cellular growth, differentiation and apoptosis. Retinoids are small sized hydrophobic and lipophilic molecules which enter cell membrane easily. Thus they can be ideal candidates for medical therapies. Retinoid supplementation has been tried as chemopreventive drug in various cancers. However, their success has been marred by contrasting reports. Their use in oral precancer has been advocated vehemently.Objective: The present review focuses on studies on oral precancer to understand the mechanism, difficulties and potential solutions to find out answers for optimal clinical use of retinoids.Material and methods: A search on pubmed was done using keywords Retinoid, Retinol, Isotretinoin and oral cancer for last 39 years spanning from 1980 to till date and which yielded 58 articles. Of these articles, 48 articles in English and involving human species were selected. Further filtering of articles was done by selecting only those whose either abstract or full text was available online. In the last, manual filtering by excluding all articles unrelated to oral cancer was done by excluding any studies involving lung, ovarian or breast cancer etc and which yielded 30 articles. Important articles referring to retinoids mechanism and use in these 30 papers were also taken making a total of 61 articles.Results & conclusions: Though retinoid supplementation seems promising in other cancers but its usefulness in oral epithelial premalignant and malignant lesion is still debatable. Large human trials are needed in this direction for treating epithelial malignancies using retinoids as a targeted therapy.