Comparison of cancers of the oral cavity and pharynx worldwide: etiological clues.

We assessed separate and combined sex-specific incidence rates of oral and pharyngeal cancer for 1988-92 and oral/pharyngeal ratios from 49 different cancer registries in five continents. Incidence trends over a period of approximately 30 years were evaluated in 16 long active registries for men and four for women. Cancers of the lip, salivary glands, and nasopharynx were excluded. The incidence of both oral and pharyngeal cancer among men is highest in northern France, southern India, a few areas of central and eastern Europe, and Latin America. Among women, the highest incidence is observed in India. Oral/pharyngeal ratio is everywhere systematically lower in men compared to women. Recent trends for oral cancer are more favourable than those for pharyngeal cancer in developing countries. In developed countries, trends in oral cancer appears to be more closely correlated to changes in alcohol consumption than those of pharyngeal cancer.