Relation between Different Stages of Oral Cancer and Aberrant Methylation in Taiwan: Preliminary Report

Objectives: During the past decade, oral cancer has become the fourth cause of death in Taiwan. After receiving treatment at the early stages of oral cancer (stage I and stage II), the 5-year survival rate is up to 81.9%. However, as soon as cancer cells spread to the neighboring tissues accompanied with lymph node metastasis in the neck (stage III and stage IV), the 5-year survival rate drops to 23-25%. This indicates the importance of the early detection of carcinogenesis to high survival rate. Aberrant methylation in promoter regions of certain genes has long been noticed and evidenced as strongly correlative to carcinogenesis. Methods: The tissue samples were obtained from the patients of one medical center, and the tissue was divided into 3 parts: tumor, nearby tissue, and further (normal) tissue. Then, the tissue was deposited in liquid nitrogen for DNA and RNA extractions. Patient data were collected including age, sex, risk factors (alcohol/betelnut/cigarette use), clinical and pathological stage, and operation. Results: This study investigates the aberrant methylation level on seven genes, E-cadherin, cyclinA1, cytoglobin, IGF2, MGMT, P16, and RARβ, in tissue samples of oral cancer. Conclusions: By means of the high sensitivity and accuracy technology, pyrosequencing, the methylation profiles of studied genes should be able to provide insight and evaluation of biomarkers of aberrant methylation in carcinogenesis.