Objective: The subtle differences between normal and tumor cells are exploited in the detection and treatment of cancer. These differences are designated as tumor markers and can be either qualitative or quantitative in their nature. This means that both the structures that are produced by tumor cells and the structures that are produced in excessive amounts by host tissues under the influence of tumor cells can function as tumor markers. An ideal tumor marker should be highly sensitive, specific, and reliable with high prognostic value, organ specificity and it should correlate with tumor stages. However, none of the oral tumor markers reported to date has all these characteristics. Apart from their limitations, tumor markers are precious tools for screening a healthy and a high risk population for the presence of cancer, making a diagnosis of a specific type of cancer, along with determining the prognosis and monitoring the course of the disease in the patient, at the time of remission or during the course of treatment. This review aims at understanding the role of tumor markers in a nutshell. Methods: This article is based largely on our experience, discussions with colleagues, reviews, and original articles on the subject, as well as on a textbook on chromosomal rearrangement in tumor cells. We used the following key words for Medline searches for cancer, tumor markers, carcinogenesis. Results: Several national and international expert groups have developed guidelines for use of markers for most cancers. None of these markers are currently validated for use in oral cancer. Conclusions: Tumor markers cannot be construed as primary modalities for the diagnosis of oral cancer. Their main utility in clinical medicine has been a laboratory test to support the diagnosis. A host of tumor markers have been described, and new ones appear every year. New investigative techniques at the cellular and molecular level show great promise at defining potentially malignant lesions but further prospective, in-depth studies are required to determine their practical usefulness. Tumor markers are reliable predominately in monitoring the treatment response, as well as in early detection of disease recurrence (prior to development of clinically notable signs). Due to their incompetence, tumor markers' determinations can be only exceptionally applied as screening methods and not as the sole diagnostic tool; however, in combination with other diagnostic methods, they play an important role in the diagnostic process and in treatment planning. Besides, by combining various tumor markers we can achieve a greater specificity and sensitivity in the follow-up of one type of malignancy. (C) 2016 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.
