Possible Underestimation of the Incidence Rate of Prostate Cancer in Japan

We adjusted the prostate cancer incidence rate in Japan for differences between Japan and the US in the proportion of latent prostate carcinoma identified at autopsy and of localized tumors among all carcinomas of the prostate. The adjusted incidence rate of prostate cancer in Japanese in Japan by this method is estimated to be between 24.9 and 33.3 per 100,000 population, based on incidence rates from the population‐based cancer registries of Miyagi, Japan, and Los Angeles and Hawaii, USA. The rate estimated here is almost 3–4 times greater than the rate reported previously. The difference in the incidence rates of prostate cancer between Japanese in Japan and the US (32.2–49.8 per 100,000) may therefore be substantially smaller than previously thought.