MUTAGEN SENSITIVITY AS A PREDISPOSING FACTOR IN FAMILIAL ORAL-CANCER

Pedigree analysis of the oral cancer (OC) patients registered at our C entre had disclosed familiar aggregation of oral cancer which hitherto has not been largely reported. There is a paucity of information on t he genetic determinism for familial oral cancer predisposition. Theref ore, we investigated constitutional chromosome abnormalities and bleom ycin-induced chromosome sensitivity of 7 familiar and 10 sporadic oral cancer patients and 14 unaffected family members (first-degree relati ves) to determine whether these factors could give any clues regarding cancer-predisposing factors. Neither the oral cancer patients nor the unaffected family members showed any constitutional chromosomal abnor malities. However, with regard to bleomycin sensitivity, there was sig nificant difference between the oral-cancer patients and unaffected re latives. The mean b/c value was 1.68 +/- 0.48 for familiar OC patients , 1.12 +/- 0.36 for sporadic OC patients and 0.52 +/- 0.18 for the una ffected family members (p < 0.001). A noteworthy observation was that one unaffected family member also showed bleomycin hypersensitivity an d expressed a mean b/c value of 1.32, at the initiation of the study. That patient later developed oral carcinoma. This clearly demonstrates that mutagen hypersensitivity among unaffected relatives in OC famili es may be related to cancer predisposition. The mutagen sensitivity st udy is being continued in a larger series of subjects, for the develop ment of a cytogenetic marker for prediction of cancer susceptibility. (C) 1996 Wiley-Liss, Inc.