Projections are that adenocarcinoma of the prostate gland will become the most common cancer affecting American men and the second leading cause of cancer deaths in this population. There are two common screening tests for prostate cancer: the serum prostate-specific antigen (PSA) and the digital rectal examination (DRE). Recommendations for the use of these screening techniques vary. The American Cancer Society and the American Urological Association recommend screening men older than 50 years using DRE and PSA. The American College of Physicians recommends that physicians counsel patients on the risks versus benefits of the screening methods. The U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to recommend either method. The rationale behind some of these recommendations is that, although these screening methods detect prostate cancer, little evidence shows that this detection reduces mortality rates. Concato and associates assessed the effectiveness of PSA with or without DRE in reducing mortality rates associated with prostate cancer.

The nested case-control analysis included men 50 years or older who received outpatient care from 10 Veterans Affairs medical centers between 1989 and 1990. Patients were included in the study if they were diagnosed with adenocarcinoma of the prostate from 1991 to 1995 and died during the follow-up period (from diagnosis to 1999). Control participants were selected from the remaining study patients and were matched with case participants based on age and treatment location. Medical records of patients in both groups were reviewed to identify patients who had been screened with PSA with or without DRE. Mortality was established using a Veterans Affairs database, and the data were adjusted for race and comorbidities.

Of 71,661 patients who met the inclusion criteria, 1,425 were diagnosed with prostate cancer, and 501 died during the study. The primary evaluation of all-cause mortality showed no benefit from PSA screening (adjusted odds ratio [OR] = 1.08; 95% confidence interval [CI], 0.71 to 1.64; P = .72). The secondary evaluation of cause-specific mortality (136 of the 501 patients with prostate cancer died because of the disease) showed no benefit from PSA screening with or without DRE (adjusted OR = 1.13; 95% CI, 0.63 to 2.06; P = .68). Black race was a predictor of cause-specific mortality, but the number of patients evaluated was small (n = 15).

The authors conclude that screening with PSA with or without DRE does not appear to effectively reduce mortality rates. The authors support recommendations that physicians counsel men on risks and benefits so that asymptomatic patients receive screening only after giving informed consent.

editor’s note: The most important factor when considering a screening test is whether the benefits of the test outweigh its risks. Historically, multiple studies have shown that potentially beneficial screening tests for detecting early prostate cancer had little or no impact on health outcomes. Therefore, the USPSTF’s guideline on prostate cancer screening, published in 2002, states that there is insufficient evidence to recommend for or against DRE and PSA screening.¹ The guideline notes that there is good evidence PSA screening can detect early-stage prostate cancer, but there is mixed and inconclusive evidence that this detection improves outcomes.¹ An editorial² concerning the study by Concato and colleagues points out that a Canadian study³ showed a more positive outcome with PSA screening.

Each study had strengths and weaknesses; therefore, physicians are still faced with the same question: does screening for prostate cancer improve outcomes? The editorial² says both studies suggested that randomized controlled trials are needed to answer this question. Two are underway; however, the results will not be available until 2009. Until then, physicians should continue to provide men with information about the risks and benefits of screening for prostate cancer, allowing patients to give informed consent before undergoing the tests.—K.E.M.