Prostate cancer screening may not reduce mortality

In the latest study to question the value of prostate cancer screening, researchers have shown that evaluation with prostate-specific antigen (PSA) testing or digital rectal examination does not reduce mortality.

"Among studies of the effectiveness of prostate cancer screening, our study is important in focusing on mortality as the outcome and in using rigorous methods to identify screening tests," lead author Dr. John Concato, from the VA Connecticut Healthcare System in West Haven, told Reuters Health. "We also have a large sample size and selected cases and controls from a community-based sample of participants."

The unclear benefits of prostate cancer screening are reflected in the different recommendations put forth by medical organizations. For example, the American Cancer Society and American Urological Association both recommend PSA and DRE screening for men older than 50 years, whereas the US Prevention Services Task Force believes that evidence is lacking to advocate screening.

The new findings, which appear in this week's issue of the Archives of Internal Medicine, are based on an assessment of 1,425 men diagnosed with prostate cancer between 1991 and 1995, identified from among more than 70,000 patients who received outpatient care at one of 10 VA medical centers in New England.

Among the group with prostate cancer, 501 men died ("cases") between 1991 and 1999. These patients were matched to 501 ("controls") selected from the prostate cancer group who were alive when the other patient died.

"Definite screening with PSA occurred in 70 cases (14 percent) and 65 controls (13 percent)," the researchers report. They point out that if screening were beneficial, the rate would be lower among the fatal cases than the controls.

The team's analysis shows that screening with PSA and digital rectal examination, either alone or in combination, did not reduce all-cause or cause-specific mortality.

As to why such screening may not improve survival, Concato noted that "men will benefit from screening only if a tumor with the potential to cause harm is detected and treated before it becomes metastatic; and this may not happen often enough for screening of healthy men to 'work'."

Concato said that while the study provides useful information on this topic, the issue of whether prostate cancer screening is worthwhile is by no means settled. The results of ongoing studies, released in the next few years, "will hopefully provide more clarity," he added.

In the meantime, Concato said clinicians should counsel their patients that "the PSA test isn't perfect, and that screening may lead to possible harm as well as potential benefit. The benefits include the potential for improved survival in some men.

The harms include possible treatment-related side effects, including incontinence and impotence, for therapies that may be unnecessary or ineffective." There is also the stress and anxiety associated with false-positive results, he added.