U.S. Trial Shows No Early Mortality Benefit from Annual Prostate Cancer Screening

The prostate cancer screening tests that have become an annual ritual for many men don’t appear to reduce deaths from the disease among those with a limited life-expectancy, according to early results of a major U.S. study involving 75,000 men.

Results released today from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial show that six years of aggressive, annual screening for prostate cancer led to more diagnoses of prostate tumors but not to fewer deaths from the disease. The study, led by researchers at Washington University School of Medicine in St. Louis and conducted at 10 sites, will appear online March 18 in the New England Journal of Medicine (and in the journal’s print edition on March 26).

“The important message is that for men with a life expectancy of seven to 10 years or less, it is probably not necessary to be screened for prostate cancer,” says the study’s lead author and principal investigator Gerald Andriole, M.D., chief urologic surgeon at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.

But it’s too soon, he added, to make broad screening recommendations for all men based on the study’s initial findings.

“So far, only a minority of men enrolled in the PLCO study have died, so it may be premature to make generalizations about the ultimate results of the trial,” he says. “We don’t have enough data yet about the youngest men in the study – those in their 50s – and it may be that over time, we will, in fact, see a benefit from screening.”

The PLCO trial began in 1992 with funding from the National Cancer Institute and was designed to determine whether prostate cancer screening reduces deaths from the disease. It involves men ages 55 to 74 who received either annual PSA blood tests and digital rectal exams or “routine care,” meaning they had the screening tests only if their physicians recommended them. After seven to 10 years of follow up, deaths from prostate cancer were very low in both groups and did not differ significantly between the groups.

Health guidelines issued last year by the U.S. Preventive Services Task Force recommend against prostate cancer screening for men age 75 or older and concluded there is insufficient evidence to assess the balance of benefits and harms of prostate cancer screening in men younger than 75. However, the American Urological Association and the American Cancer Society recommend annual prostate cancer screening tests beginning at age 50 for most men.

More than 186,000 U.S. men will be diagnosed with prostate cancer this year, and nearly 29,000 will die from the disease, according to the National Cancer Institute. PSA blood tests, introduced in 1988, have increasingly been used as a screening tool for prostate cancer, despite a lack of evidence showing they reduce death rates from disease.

The controversy over prostate cancer screening has arisen because most men who undergo a biopsy for an abnormal PSA test do not have prostate cancer. For those who have cancer, the tumors generally grow so slowly that most men die of other causes. Furthermore, prostate cancer treatment can result in incontinence and impotence. However, some tumors can be aggressive, and the difficulty has been distinguishing aggressive cancers from those that are slow growing.“We definitely need to find better ways to detect and treat aggressive tumors, those that are truly life-threatening, so that men with slow-growing tumors can avoid unnecessary treatments,” says Andriole.