Prostate cancer in Saskatchewan Canada, before and during the PSA era

The purpose of this study was to describe changes in the incidence of prostate cancer and in survival of diagnosed cases, as well as prostate cancer-specific mortality, during a period spanning the introduction of prostate specific antigen (PSA) testing in Saskatchewan in 1990.

All cases of neoplasms of the prostate (ICD-O = C61.9) diagnosed in Saskatchewan from 1970 to 1997 inclusive, were identified in the Saskatchewan Cancer Registry. A subgroup of adenocarcinomas was defined for further study. Age-adjusted and age-specific incidence rates, and actuarial and relative survival were calculated according to time period of diagnosis. Age-adjusted and age-specific mortality rates from prostate cancer were also calculated for each time period, using Vital Statistics data.

The age-adjusted incidence of prostate cancer was 60.5 per 10(5) in 1970, rising gradually to 101.5 per 10(5) in 1989. In 1990, incidence rose much more sharply, reaching a peak of 163.1 per 10(5) in 1993, after which it began to fall. This sharp increase coincided with the introduction and increasing use of the PSA test in the province. Relative survival of prostate cancer patients was stable from the late 1970s through the 1980s, then improved markedly in the 1990-94 period. After the introduction of the PSA test, the relative risk of death for prostate cancer patients was only about 60% of what it had been throughout the previous 15 years. Prostate cancer-specific death rates did not change from the early 1980s to the end of the study period.

The above data are consistent with earlier diagnosis of prostate cancer due to PSA screening. Because mortality has not yet changed, it is premature to recommend widespread screening of asymptomatic men.