The role of genetic susceptibility in head and neck squamous cell carcinoma.

Our research is an additional genetic study to uncover the molecular mechanisms involved in head and neck squamous cell carcinoma (HNSCC) pathogenesis by studying loss of heterozygosity (LOH) and microsatellite instability (MSI) in both premalignant and malignant patients and to highlight the genotype of HNSCC in Upper Egypt. Patients with HNSCC from various parts of the world may have unique genotypes and this is the first genetic study of HNSCC in Sohag 500 KM to the south of Cairo. We performed a prospective study of 41 patients with precancerous and 79 patients with cancerous laryngeal, esophageal, nasopharyngeal, nasal and oral lesions, and 50 controls (The control patients were cases admitted for ear surgery or simple nasal surgery, from whom we took biopsy from mucosal lining of nasopharynx). The present study included 170 individuals who were admitted to the Ear, Nose and Throat department, Sohag University Hospital, Sohag, in Egypt in the period between April 2001 and March 2003. Samples which were taken by punch biopsy were frozen and stored at -80 degrees C and were subjected to histopathological examination. We investigated LOH and MSI by using six microsatellite markers located at chromosomes 3, 5, 9, and 17. The markers used were D3S1286, D9S171, D9S753, D17S654, D17S695, and CFS1-R. LOH was in all premalignant and malignant lesions at 5q33.3-q34 and 13% of Controls. LOH at 17p21 was absent in all premalignant lesions and was found in 53% of malignant lesions and 12.4% of Controls. In premalignant lesions, LOH was at 3pter-3p24.2 (73% of cases), at 9p21 (46%), at 9q21.1-22.3 (37%), and at 17p13 (37%). These percents increased in malignant lesions to 87, 80, 67, and 63%, respectively. They were 14, 19.4, 17, and 19% in controls. Examination of LOH could improve diagnosis, adds additional confidence, in HNSCC by DNA extraction from suspicious lesions in high-risk groups (smokers and alcoholics) and LOH at 3p/9p seems to be of particular value for early detection and definition of progression risk. If there are high percent of LOH at these chromosomes, active intervention should be done (chemoprevention and regular follow up head and neck examination for very early detection and management).