Repair Index in Examination of Nuclear Changes in the Buccal Mucosa of Smokers: A Useful Method for Screening of Oral Cancer

Background: Smoking is one of the major risk factors for cancers, especially in the oral cavity. Nuclear changes occur in the early stages of cancer. The aim of this study was therefore to investigate nuclear changes and calculate a “repair index” for the buccal mucosa of smokers. Material and Methods: This historical cohort study was conducted by selecting samples including smokers and non-smokers. In addition, the smoker group were divided into 2 subgroups with a smoking history of >10 and ≤10 years. Buccal mucosa smears were obtained and Papanicolaou staining was employed to detect nuclear changes. Micronuclei, karyorrhexis and karyolysis were assessed and eventually a repair index was calculated. Statistical analysis was performed using the t-test. Results: In the 60 samples studied, differences were significant in smopkers vs. nonsmokers for micronuclei, (P=0.002) but not karyorrhexis or karyolysis. (P=0.789 and P=0.578, respectively). Also, the repair index demonstrated no statistically significant variation (P=0.107). Comparison of the two subgroups of smokers demonstrated that the frequency of micronuclei in those with a history >10 years was significantly higher and the RI was significantly lower than with ≤10 years (P=0.0001 and 0.04, respectively). While karyorrhexis and karyolysis were also higher in the longer exposure individuals the differences were not significant (P=0.07 and 0.78, respectively). Conclusion: Among the nuclear changes investigated, micronuclei proved the more reliable indicator to assess the adverse effects of smoking on the oral mucosa, becoming prominent with increase in smoking history. In addition, while a “repair index” may have benefits for assessment of nuclear damage caused by smoking, further research is necessary in this field.