Microsatellite Instability Associated with Primary Head and Neck Cancers and Secondary Esophageal Cancers

Background: It is common that patientswith head and neck cancers have secondary malignant neoplasm of esophageal cancer. Methods: Toknow the genetic backgroundof the developmentof these secondary cancers,we performed microsatellite assay at six loci and immunohistochemical analysis on head and neck cancers of eight patientswith esophagealcancer and on those of 19 patientswithout esophageal cancer. Results: Replication error (RER) at morethan two lociwas observedin two (25%)of eight double cancer patients, whereas it was not observed in the patients without the secondary cancer. Immunohistochemically, overexpression of cyclin 01 was detected in two (25%) of eight double cancer cases and in two (11 %) of 19 non-double cancer cases, respectively, the incidence showing a higher tendency in the former. Conclusions: The results suggest thatmicrosatellite instability maybe implicated in thedevelopment of head and neckdouble cancers and that RER (+) phenotype may serve as a biomarker to predict the development of secondary esophageal cancer in patients with head and neck cancer. Key words: second malignant neoplasms- head and neck cancer- esophageal cancer- microsatellite instability- immunohistochemistr