Mass screening for prostate cancer: a comparative study in Natori, Japan and Changchun, China.
OBJECTIVES: To study the natural background of prostate cancer in Japan and China, mass checks with prostate-specific antigen (PSA)-based screenings were performed using identical procedures in Natori, Japan and Changchun, China. METHODS: For 7 years (1995 to 2001) in Natori, Japan, and for 3 years (1998 to 2000) in Changchun, China, 2212 Japanese and 3566 Chinese men older than 55 years were mass checked by PSA-based screening (serum PSA cutoff value 4.1 ng/mL). RESULTS: The PSA-positive rates (PSA 4.1 ng/mL or greater) and cancer detection rates in the screened persons of Natori and Changchun were 8.5% and 5.2% (P <0.0005) and 2.1% and 0.8% (P <0.0001), respectively. When the number of cancer cases detected was adjusted to a 100% biopsy rate for men who were PSA positive in both cities, the cancer detection rate was estimated at 2.3% and 1.3% in Natori and Changchun, respectively. This difference was also significant (P <0.01). CONCLUSIONS: The results indicate that the percentage of PSA-positive men 55 years or older in Changchun was lower than that in Natori. The analysis of the results suggests that the prostate cancer incidence and prevalence in Changchun, China are lower than those in Natori, Japan.