Yearly PSA Screening Found to Cut Prostate Cancer Mortality

Annual screening for prostate specific antigen (PSA) reduced the risk of dying from prostate cancer, researchers reported.

In a retrospective study of 1,492 prostate cancer patients, those who had not had yearly screens were three times more likely to die of prostate cancer over the next 10 years than men who got an annual PSA test, Boston researchers reported at a meeting here of the American Society for Therapeutic Radiology and Oncology.

All the men in the four-year study had been diagnosed with clinically localized prostate cancer and had had a radical prostatectomy during the course of the study but then experienced biochemical failure (PSA higher than 0.4 ng/ml), said Jason Efstathiou, M.D., a clinical fellow in radiation oncology at Brigham and Women’s Hospital and the Dana-Farber Cancer Institute.

Of this group, 841 men had had yearly annual PSA screens before their diagnosis. The rest (611 men) were prostate cancer patients referred from community-based practices. It was not clear whether any of these men had been screened with PSA.

In the study, the 811 PSA-screened men fared better on almost every score, Dr. Efstathiou said. For example their mean PSA level at the time of diagnosis was 5.1 ng/mL versus 9.5 ng/mL in the community referrals (p<.0001). About 25.1% of the 811 screened men had aggressive cancers, as indicated by a pre-op Gleason score of 7 to 10, compared with 42.1% of the 611 community men (P<.0001).

Within three months of prostate cancer surgery, PSA levels doubled in only 4.6% of the screened men, compared with 12.1% of the community referrals (P<.0001). PSA doubling three months after surgery is a surrogate endpoint for prostate cancer death, Dr. Efstathiou said.

The researchers estimated that over 10 years, 11.3% of men who don’t have annual PSA screens would die from the disease, compared with 3.6% of those who had yearly tests. That was a greater than threefold difference that reached statistical significance (p=.0002), Dr. Efstathiou said.

“This simple yearly blood test would appear to discover prostate cancers at an earlier, less aggressive stage and may lower the risk of dying from prostate cancer,” Dr Efstathiou concluded.

The American Cancer Society and the American Urological Association have both backed annual PSA screening of men over 50. The U.S. Preventive Services Task Force has not. Many physicians believe that the cost is not worth the number of life-threatening cancers that are detected by annual screening.

“We really need the results of three massive randomized trials going on in the U.S. and Europe.” Dr. Efstathiou said. Those results will not be reported until at least 2008.

However, “our findings do give us clues into what I expect the large trials will show,” he said. “If those studies confirm the results of this trial, annual PSA testing will become standard.”

Theodore Lawrence, M.D., chairman of radiation oncology at the University of Michigan in Ann Arbor, agreed that the so-called PSA doubling time is a “reasonable surrogate endpoint for survival.” But any findings from a retrospective trial may be subject to selection bias, he said.

“There’s no question that PSA can detect early-stage prostate cancer, but the question is whether it will improve survival and lower deaths from prostate cancer,” Dr. Lawrence said. “We’re still waiting for the answer to that question”

Source: American Society for Therapeutic Radiology and Oncology 47th annual meeting

Print Version
Tell-a-Friend