[Chronological changes of incidence rates, clinical stages and pathological differentiation of prostate cancer in Gunma Prefecture, Japan].

Prostate cancer is the most common urogenital cancer, and is increasing rapidly. We performed an epidemiological study on prostate cancer in Gunma Prefecture, Japan. Registration of prostate cancer patients diagnosed at clinics and hospitals in and around Gunma Prefecture was started at Gunma University in 1985. The epidemiological characteristics of prostate cancer patients in Gunma Prefecture were analyzed by these data. The incidence and crude incidence rates have increased five-fold, from 114 and 12.0 in 1985 to 539 and 53.9 in 2000, respectively. The age-adjusted incidence rate (adjusted to the world population) was increased three-fold, from 8.3 in 1985 to 24.2 in 2000. The age-specific incidence rate showed an increase with age. The cancers in clinical stages A and D decreased, while those in stages B and C increased. No change in distribution was observed in pathological differentiation. Prostate cancer has increased rapidly during these 16 years in Gunma Prefecture. It is important to perform PSA testing aggressively in males age 50 or older, and detect prostate cancer in an early stage.