Risk of progression and dying of clinically localized prostate cancer in Japan

Detection of prostate cancer by prostate-specific antigen

The use of prostate-specific antigen (PSA) for early detection of prostate cancer has dramatically increased the reported incidence of this malignancy but its net benefit is unclear and remains controversial at present. Although several countries have adopted prostate cancer screening as a health policy, a reduction of cancer mortality would be an ultimate indication of the effectiveness of early detection. Since screening upon patient request cannot be refused, appropriate information should be provided until further support is available.

Public awareness and knowledge of prostate cancer in Japan: results of a survey at short-stay examination facilities

BACKGROUND

This study was undertaken to determine public awareness and knowledge of prostate cancer, which has not been adequately studied in Japan.

METHODS

Assessment was made of public awareness and perception of prostate cancer in Japan, based on health examination data for participants in a short-stay physical examination program ("human dry dock"). A multiple-choice, thirty-point questionnaire survey was conducted at 3 "human dry dock" medical facilities situated in urban areas.

RESULTS

Many Japanese adults appeared to be inadequately aware of prostate cancer and of the means available for its early detection. One third of the participants were unfamiliar with this malignancy. Logistic regression analysis indicated smoking to be the only covariate associated with lack of knowledge of prostate cancer (P< 0.05). Seventy-one percent of the subjects had heard of digital rectal examination, but only 16% and 8%, respectively, were familiar with the terms transrectal ultrasonography and PSA testing. Japanese people may possibly be less informed about prostate cancer than African-American males. Both "human dry dock" facilities and subject gender were significantly associated with knowledge of digital rectal examination (P< 0.05). Knowledge of transrectal ultrasonography was found to depend on participation in "human dry dock" programs and level of education (P< 0.05). Smoking, participation in "human dry dock" programs under employer direction, and health status were all identified as determinants for knowledge of PSA testing (P< 0.05).

CONCLUSION

Educational programs should be established and put into effect to instill adequate awareness of prostate cancer in Japan. In a better-informed society, more effort would be directed toward prevention and thus early stage prostate cancer would be detected more often.

Impact of life expectancy and tumor doubling time on the clinical significance of prostate cancer in Japan

Theoretical projected prostate cancer volume at the time of expected death was determined based on patient age and index cancer volume at diagnosis, assumed cancer volume doubling time and life expectancy of the Japanese male population. Based on the data obtained, evaluation was made of the results for 104 consecutive radical prostatectomy cases with no prior treatment. Clinically insignificant cancer in 104 prostatectomy specimens was found to occur at 4.8, 10.6, 15.4 and 26.9% for tumor doubling times of 2, 3, 4 and 6 years, respectively. Assuming a 2-year doubling time with clinically insignificant cancer excluded, only 36.4% of significant cancers could be considered potentially curable and with a 3-year doubling time, 32.3%. For 4- and 6-year doubling times, only 30.7 and 25.0% of the clinically insignificant cancers were potentially curable, respectively. Approximately half of these insignificant cancers were clinically stage T1c disease. In all stage T1c cases, 8.8-47.1% was considered insignificant, depending on tumor doubling time. Patient life expectancy and tumor doubling time significantly determine the outcome of treatment for prostate cancer, especially in elderly males with higher risk of mortality. The outcome of radical prostatectomy is less satisfactory with these factors taken into consideration. Many patients with stage T1c disease may eventually prove to require no treatment.