RESUMO
Sister chromatid exchange (SCE) was studied in PHA-stimulated peripheral blood lymphocytes from 81 untreated patients with squamous cell carcinoma of the oral cavity and 50 age and sex matched controls. The SCE frequencies were found to be 10.80 +/- 1.38 and 4.15 +/- 1.15 in cancer cases and controls respectively. The SCE values of cancer cases deviate significantly from that of controls. The SCE frequency in patients who were addicted to the single habit of betel with tobacco chewing or bidi/cigarette smoking or combined habits of chewing and smoking was 9.38 +/- 1.28, 12.28 +/- 1.68 and 13.12 +/- 2.13 respectively. The SCE frequency in patients who were habituated to alcohol and tobacco usage was 13.43 +/- 2.16. These values were significantly higher as compared with the SCE values observed in normal controls. Single habit of bidi, cigarette and combined habit of bidi and cigarette smokers had a mean SCE per cell of 12.98 +/- 2.11, 10.18 +/- 1.25 and 13.48 +/- 1.32 respectively, which were significantly higher than the mean value of 4.15 +/- 1.15 found in controls. Higher frequencies of SCE were also observed in individuals who smoked more than 10 bidis or cigarettes per day compared with people who smoked less than 10 bidis or cigarettes per day. Individuals who smoked bidis or cigarettes for more than 10 years also showed an increased frequency of SCE as compared with those who smoked bidis or cigarettes for less than 10 years. Among chewers a significant difference was observed with regard to duration and frequency of chewing when compared to controls. An increase in the mean frequency of SCE for each cancer patient group is directly proportional to the clinical stage of the disease. Interchromosomal distribution of SCE revealed an increased frequency of SCE in almost all the groups of chromosomes in cancer patients when compared to controls.