TARA PARKER POPE | NYT NEWS SERVICE

UPDATED findings from one of the largest studies of prostate cancer screening show that the commonly used PSA blood test did not save lives, although questions remain about whether younger men or those at very high risk for the disease might benefit.

Last fall, the United States Preventive Services Task Force concluded that healthy men should no longer be routinely screened for prostate cancer using the prostate-specific antigen, or PSA, blood test. That decision was based on findings from five well-controlled clinical trials, including a major American study called the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, which studied PSA testing in nearly 77,000 men ages 55 to 74.

In 2009, the PLCO trial reported that although annual PSA screening did detect more cancers, it didn’t save more lives when compared with a group of men who were given routine medical care and tested for prostate cancer only when a problem was suspected. But at the time, the investigators had only 7 to 10 years of data.

Because prostate cancer can take several years to develop, the investigators continued to collect data after reporting the initial findings.

In a new paper published in The Journal of the National Cancer Institute, the scientists report that the additional follow-up time didn’t change the overall conclusion: that regular PSA testing does not save lives and can lead to aggressive treatments that leave men impotent, incontinent or both.

The PSA test, often given to men starting at age 50, detects a protein called prostate-specific antigen and can identify the presence of cancerous cells in the prostate. Although about 12 percent more cancers were found among men in the screening group, the risk of dying of prostate cancer in the study was about the same for each group, whether the cancer was detected through screening or because a man developed symptoms.

The findings suggest that the type of cancer typically detected by screening is so slow-growing that it often is unlikely to cause harm before the man dies of another cause.

“Despite additional follow-up, there is no demonstrable mortality benefit for the men who had PSA testing compared to the usual care group,” said Dr Gerald L Andriole, the lead author and chief of urology at Washington University School of Medicine in Saint Louis.

Even so, the findings are unlikely to resolve the debate around PSA testing. Many doctors argue that the trial was seriously flawed because about half the men in the non-screening group ended up getting one or more PSA tests during the trial period, making it difficult to determine the real effect of screening.

After the study was finished, additional analysis also raised questions about whether certain younger, healthy men might benefit from PSA testing. Although only about 300 men out of the 77,000 studied ended up dying of prostate cancer, the test appeared to have saved a few extra lives among younger men.