Purpose: The incidence of prostate cancer is increasing in Asian countries. Studies using prostatectomy specimens have reported a racial difference in tumor location within the prostate, with a greater incidence of transition zone cancer in Asian men compared with Caucasian men. However, there may be potential biases in studies based on surgical specimens. We describe the pathological features of subclinical prostate cancer, such as latent cancer and incidental cancer, to elucidate tumor location of contemporary Japanese patients. We also compare the prevalence of latent and incidental prostate cancer to determine whether the incidence of prostate cancer is higher in patients with bladder cancer.
Materials and methods: Overall 182 men autopsied and 148 who underwent cystoprostatectomy for bladder cancer were included in the study. Each prostate gland was fixed and sliced in step sections. Histological evaluation was performed by a single genitourinary pathologist. The index tumor location was categorized into transition zone or peripheral zone.
Results: Prostate cancer was found in 39.0% of the autopsy specimens and 31.6% of the cystoprostatectomy specimens. The prevalence and pathological characteristics were not significantly different between latent and incidental cancer. The prevalence of transition zone cancer was 39.0% (46 of 118). In elderly men peripheral zone cancer was more frequently diagnosed than transition zone cancer (p=0.049). The pathological characteristics of transition and peripheral zone cancers were similar except for the pT stage.
Conclusions: Transition zone cancer was prevalent in contemporary Japanese men. The incidence of prostate cancer in men with bladder cancer might not be higher than that in healthy men.
Keywords: Japan; incidental findings; pathology; prostatic neoplasms.