International trends in prostatic cancer.

The most recent data available demonstrate a 120-fold difference between the lowest and highest incidence rates of prostatic cancer, the disease being very common in North America, particularly among Blacks, and in Scandinavia, while it is rare in Japan and other oriental countries. The highest mortality for prostatic cancer is reported from St. Vincent and Grenadines, Martinique and Bermuda, from countries where the morbidity statistics are not available; the mortality rates reported from the United States and Canada are considerably lower. The incidence of and mortality from prostatic cancer have increased in most countries, in particular in areas with an initially low frequency of this disease. The ratio of mortality to incidence for prostatic cancer varies rather widely, being low in North America, Hawaii and Scandinavia. It is suggested that the observed variation in the mortality to incidence ratio for prostatic cancer could be due to differences in diagnostic practices between countries. This could explain, at least in part, the fact that the increasing trends of prostatic cancer incidence in North America are not accompanied by an increase in mortality from this tumour. This notion, however, does not exclude advances in treatment as possible determinants of the improved survival rate from prostatic cancer in this part of the world. The available statistics on prostatic cancer are based on the sum of clinically diagnosed carcinomas and those latent tumours found unexpectedly at prostatectomy and autopsy. The proportion of latent carcinomas among all prostatic cancer cases depends on the detection rate and varies from country to country, thus casting uncertainty on the comparability of prostatic cancer statistics from different areas. To avoid confusion in the statistics of prostatic cancer, it would be useful to consider introducing latent prostatic cancer as a separate entity in the next revision of the International Classification of Diseases (ICD).