Histological differentiation of oral squamous cell cancer in relation to tobacco smoking.

The aim of this study was to assess the potential effect of tobacco and alcohol consumption on the histological differentiation of oral squamous cell carcinomas in 161 consecutive patients. The patients were included in a prospective study to secure valid data on tobacco and alcohol consumption. The histopathological grading system included eight morphological qualities describing both the tumour cell population and the interaction between tumour and host. A mean histological score was calculated as the arithmetic mean of the scored individual morphological parameters. Tobacco consumption, as opposed to alcohol consumption, was shown to be significantly correlated with the mean histological score (P = 0.0009), and with the four morphological qualities describing the tumour cell population: pattern (P = 0.0044), cytoplasmic differentiation (P = 0.0008), nuclear differentiation (P = 0.0054) and mitosis (P = 0.0001). Thus, tobacco consumption seems to cause the tumour cells of oral squamous cell carcinomas to undergo a more pronounced dedifferentiation which makes them more aggressive. This effect is enhanced with increasing exposure to tobacco smoke.