Prostate-specific antigen in a community screening program

Journal of Family Practice, August, 1995 by Kendra L. Schwartz, Tsui-Ying Kau, Richard K. Severson, Raymond Y. Demers

Background. This study was designed to determine who participates in community-based prostate-specific antigen (PSA) screening programs and what serum PSA levels can be expected.

Methods. A descriptive analysis of men who participated in an annual community health screening program was used to compare men who chose PSA screening with those who did not. The relationship of demographic variables to PSA level was evaluated by multivariate regression analysis. Data were available on 5548 men, 6% of whom were black.

Results. The population of PSA screening participants included proportionately more middle-aged white men with higher median income, as compared with men who did not participate. Those who did not participate in the screening were more likely to be either very old or very young. PSA levels increased with age, and the percentage of men with elevated PSA levels increased with age. One tenth (9.6%) of all participants had PSAs between 4 ng/mL and 10 ng/mL, and 1.9% had levels greater than 10 ng/mL. Within 1 year of the screening, 1.7% of the screened participants had a diagnosis of prostate cancer. The mean PSA in this group was 15.9 ng/mL.

Conclusions. These data confirm the need for age-specific PSA reference ranges. It is likely that the same reference range can be used for all racial and ethnic populations.

Key words. Prostate; prostate-specific antigen; prostate cancer screening; community health screening; community health services. (J Fam Pract 1995; 41:163-168)

In the United States, prostate cancer has surpassed lung cancer as the most commonly diagnosed cancer among men and is the second leading cause of cancer death in men. The association between age and prostate cancer is well known: the incidence rate in men over 65 years of age is almost 40 times greater than in men under 65 years.(1) As the at-risk population continues to increase, the number of prostate cancer cases also is expected to rise.

Prostate-specific antigen (PSA) has been proposed as a screening tool for prostate cancer, although its value as such has not been completely determined. Its main proven utility has been to monitor the progress of prostate cancer and the response to therapy.(2) However, the American Cancer Society currently recommends a PSA determination along with digital rectal examination annually for screening all asymptomatic men aged 50 years and older.(3) Other cancer-interest groups such as the US Preventive Services Task Force and the International Union Against Cancer do not recommend mass screening for prostate cancer because such screening has not been shown to have an impact on prostate cancer mortality.(4)

Project Health-O-Rama (PHR) is an annual community-based health-screening program in southeast Michigan that offered PSA testing as part of its screening program for the first time in 1992. Data from the 1992 program were used to determine the predictors of participation in PSA screening and predictors of PSA level in men who had a PSA test. The PHR data set permitted the following: (1) examination of the demographics of participants vs nonparticipants in PSA screening; (2) evaluation of variables associated with elevated PSA levels in a volunteer population; and (3) matching of the PHR data set against the Surveillance, Epidemiology, and End Results (SEER)(1) database for metropolitan Detroit to determine subsequent prostate cancer diagnosis. Specifically, the authors assessed whether age, race/ethnicity, and socioeconomic status influenced the likelihood of having a PSA test, and evaluated the association of age, race/ethnicity, and subsequent diagnosis of prostate cancer with PSA level.

Methods

The goal of PHR, an annual community-based health-screening program in southeastern Michigan, is to encourage individuals in the community to assume responsibility for their health and well-being by adopting and maintaining good health and lifestyle habits. In 1992, a total of 37,334 persons 18 years of age and older participated in screenings at 99 different neighborhood sites, such as shopping malls, hospitals, and churches. A multitude of screening tests and services, such as blood pressure measurement, Papanicolaou smear, prostate/testicular examination, blood chemistries, and tests for visual and hearing acuity, glaucoma, and stool occult blood, were available. Although not all tests were available at each site, blood testing was available at all sites, and because of the large number of participants, all laboratory tests, including PSA, were offered at a reduced cost.

A total of 14,022 men participated in PHR. All were offered a PSA test at a cost of $25. Solicitation regarding the PSA test consisted of distributing a 1-page handout about PSA screening to all men. The handout explained the test, its limitations, and the need for further evaluation if the PSA level was found to be elevated.

Of the 14,022 male PHR participants, 6001 purchased a PSA test (PSA participants). PSA participants were characterized by the demographic information obtained from registration forms and laboratory result forms.