Tumours in Iceland. 6. Tumours of the urinary bladder, ureter and urethra. A histological classification and some epidemiological and environmental factors.

All primary tumours from the urinary bladder, ureter and urethra submitted for a histological diagnosis in Iceland during the 20 years, 1955-1974, and available for review, were typed histologically according to the World Health Organization Classification published in 1973. The series included 237 tumours, and of these 94.5 per cent were from the bladder. Transitional cell carcinomas constituted the largest group, or 120 in males and 77 in females. For transitional cell carcinomas there was a good correlation between growth patterns, grades and pathological stages. Most of the papillary carcinomas were of grades 1 and 2 and all the purely infiltrating carcinomas were of grade 3. The papillary carcinomas were predominantly superficial and the purely infiltrating were deeply invasive and the degree of cellular anaplasia increased with the depth of invasion from the lamina propria to perivesical tissue and other organs. The incidence of transitional cell carcinoma of the urinary bladder is rising in Icelanders and the incidence in females is the highest reported among European nations. Industrial chemical carcinogens are an unlikely cause of bladder carcinoma in Icelanders but cigarette smoking, and a high consumption of coffee and salted food may play an important role.