Early detection of prostate cancer. Results of a prostate specific antigen-based detection program in Japan.

Background: Prostate cancer increasingly is becoming a medical problem in Japan. To maximize the chance for cure, extensive effort is being made to detect prostate cancer while confined to the gland.

Methods: Determination was made of serum prostate specific antigen (PSA) in the early detection of prostate cancer in an Asian male population aged 55 years or older. Recommendation for biopsy was based solely on this parameter when its value exceeded 2.0 ng/ml in IMx immunoenzymetric assay.

Results: Of 1189 men, 150 (12.6%) had elevated values. The proportion of males with serum PSA greater than 4.0 ng/ml was only 3.4%. Of the 99 males who underwent ultrasound-guided biopsies, 16 cancers were detected, a cancer detection rate of 1.3%. Most of these (81.3%) were clinically localized cancers. Seven patients with cancer had serum PSA levels below 4.0 ng/ml including 5 less than 3.0 ng/ml. These tumors would have been overlooked if the conventional cutoff levels of 4.0 ng/ml had been applied. Radical prostatectomy was conducted on 13 patients. All had histologic features of clinically significant cancer and 69.2% were pathologically confined within the gland.

Conclusions: Elderly Asian males appear to have lower serum PSA than their Western counterparts. The optimal cutoff of serum PSA for early detection should be examined further in Asian male populations. Differences in the incidence of prostate cancer between ethnic groups may have been overestimated in previous studies owing in part to unawareness by the physician and general public. Though the frequent use of more sophisticated diagnostic modalities will likely disclose greater numbers of prostate cancers in Japan, whether early detection reduces mortality by minimizing risk of death from cancer remains a point to be determined.