Exfoliative cytology of normal buccal mucosa to predict the relative risk of cancer in the upper aerodigestive tract using the MN-assay.

The high frequency of second or third primary tumors was first explained by Slaughter et al. with the concept of field cancerisation. Another theory postulates micrometastatic lesions as a reason for this phenomenon. The micronuclei (MN)-assay was evaluated to provide evidence for the concept of field cancerisation and to quantify the premalignant field change of normal mucosa in order to predict the individual cancer risk. MN-assay was carried out in 55 patients with squamous cell carcinoma of the head and neck, in 16 patients with a leucoplakia and in 99 healthy controls. A detailed questionnaire for population monitoring was completed. Buccal cytosmears of healthy mucosa of the study participants were examined for the MN count per 1000 cells. There was a direct correlation between tobacco abuse and increasing MN count as a sign of a cytogenetic damage of buccal mucosa cells. Alcohol did not influence the formation of MN. Both buccal sites were damaged in the same degree as proof of field cancerisation. The relative cancer risk (odds ratio) for smoking healthy controls with a definite MN frequency was estimated. Our study underscores the importance of the MN-assay as a biomarker to predict the relative cancer risk in the upper aerodigestive tract under suspicion of the individual susceptibility and the exposition to known carcinogenic agents such as tobacco and alcohol. The concept of field cancerisation was confirmed.