The aim of the present study was to determine the changes to the expression levels of fragile histidine triad (FHIT), breast cancer type 2 susceptibility protein (BRCA2), MutL homolog 1 (MLH1) and tumour protein 53 (p53) exhibited by families with a history of oesophageal cancer in a region that has a high incidence of oesophageal cancer, and to determine the association of these changes with the cancer history of the families. Immunohistochemistry was used to detect the protein expression of FHIT, p53, BRCA2, and MLH1 in the excised specimens of cancer tissues from 74 oesophageal cancer patients (positive family history of oesophageal cancer [OCFH +], n=33; negative family history of oesophageal cancer [OCFH -], n=41) from a region with a high incidence of oesophageal cancer. The positive expression rates of FHIT (61%; 45/74), BRCA2 (50%; 37/74) and MLH1 (27%; 9/33) in the oesophageal cancer tissues were significantly lower than those in the healthy tissues adjacent to the cancer (97% [29/30], 87% [26/30] and 73% [25/41], respectively). A significant difference was identified between the positive expression rates (P<0.01). However, FHIT, p53, BRCA2 and MLH1 expression demonstrated no significant affect on clinicopathological changes, such as oesophageal cancerous tissue differentiation, the degree of infiltration and cancer cell metastasis. The FHIT, BRCA2 and MLH1 expression levels were identified to be significantly lower in the cancer tissues from OCFH + patients. This result indicates that the expression levels of FHIT, BRCA2, and MLH1 are important molecular indices of genetic susceptibility to oesophageal cancer.
Keywords: breast cancer type 2 susceptibility protein; esophagus cancer; fragile histidine triad; genetic predisposition; mixed lymphocytic-histiocytic lymphoma; positive family history.