Tumor risk assessment by means of immunocytochemical detection of early pre-malignant changes in buccal smears.

Increasing incidence of carcinomas in the upper aero-digestive tract, both in Germany and in other European countries requires development of new preventive strategies. The cure rate at advanced tumor stages remains poor in spite of a variety of available therapeutic methods. In the present study the quantitative assessment of a pre-malignant mucosa lesion within a field cancerization was performed by means of immunocytochemical methods. This may allow individuals with an increased risk of developing malignant disease to be identified. Cytosmears taken from healthy buccal mucosa of tumor patients (n=50) and from healthy probands (n=100) with different tobacco and alcohol consumption levels were examined with regard to identifying increased expression of the proliferation markers (PCNA, MIB1), of the tumor suppressor gene product p53 as well as the oncogene product cyclin D1. There was a significant difference in expression of investigated proliferation markers between tumor patients and healthy probands (p<0.0001). When comparing the rate of positively marked cell nuclei to cigarette pack years the marker cyclin D1 and MIB1 show an increased rate in the groups with high tobacco consumption as compared to the group with a low exposure (p>0.05). It could be possible to use the marker MIB1 and cyclin D1 to screen risk groups, since the relative morbidity risk (odds ratio) increases (by 45-62 times) if the threshold value of 4 positively marked cell nuclei is exceeded.