Comparison of canine oropharyngeal malignancy in various geographical locations

The variation in prevalence of neoplasms over time and location has been of value in identifying environmental carcinogens. Studies on the relative frequency of the different histological types of canine oropharyngeal malignant neoplasm have shown that squamous cell carcinoma of the tonsil occurs four times more commonly in south east England, and twice as frequently in the United States of America as in Melbourne, Australia. The prevalence of tonsillar squamous cell carcinoma in London in 1950 was 15 times greater than that currently experienced in Melbourne and four times greater than that now found in other areas of south east England.