PSA Screening Has Similar Sensitivity to First Prostate Cancer Biopsy

Barbara Boughton

November 11, 2010

November 11, 2010 (San Francisco, California) — A retrospective analysis of 1665 patients who underwent prostate biopsies at a New York medical center has found that a first prostate biopsy has a sensitivity of about 80% — a rate comparable to that of the prostate-specific antigen (PSA) test, according to research presented here at the American Society for Clinical Pathology 2010 Annual Meeting.

Although the researchers found that the specificity of the PSA test was about 50%, 96% of patients at the Veterans Administration New York Harbor Health Care System found to have prostate cancer on biopsy underwent biopsy only because of elevated PSA, the researchers said.

"We concluded that PSA is an excellent marker for prostate cancer, since it has a similar sensitivity to a first prostate biopsy and is less invasive with less risk of morbidity," said senior author Matthew Pincus, MD, PhD, professor of pathology at the State University of New York (SUNY) Downstate Medical Center in Brooklyn.

"Another important finding was that some of the patients who had initial negative biopsies but persistently high PSA values — about 22% — were found to have prostate cancer after a second, third, or fourth biopsy," Dr. Pincus added.

Previous studies have found that the sensitivity of the PSA test is about 85%, and that the test will sometimes miss even high-grade prostate cancers. These findings suggest that the most reliable means of detecting prostate cancer is biopsy, Dr. Pincus said.

To test this assertion, Dr. Pincus and his fellow researchers performed a retrospective analysis of all patients with elevated PSA levels and a diagnosis of prostate cancer from 2000 to 2007 at the Veteran's Administration New York Harbor Health Care System. Of 1665 patients who underwent prostate biopsies, 232 had persistently elevated PSA levels and were biopsied at least twice. Of patients who underwent a biopsy for prostate cancer, 3% received as many as 3 biopsies, and 1 patient received 4 biopsies, before being correctly diagnosed with prostate cancer, Dr. Pincus noted. Of patients who received a minimum of 2 prostate biopsies, 85% had Gleason scores between 6 and 7, but 10% had higher Gleason scores, the researchers said.

"What that means is that you can have an aggressive cancer that can be missed by biopsy. In some cases, the only reason that patients with high Gleason scores were biopsied more than once was because of high PSA values," Dr. Pincus said.

Why did first prostate biopsies miss cancer in a significant number of patients? "We haven't fully ascertained the reasons for that, but we think it may have been due to sampling error," Dr. Pincus said.

The researchers also found that all patients who had a PSA of 40 ng/mL were found to have prostate cancer. "If a patient has a very high PSA — perhaps over 20 ng/mL — but a negative biopsy, then it might be wise to repeat the PSA more frequently than every year," added presenting author Weijie Li, MD, also from the SUNY Downstate Medical Center.

Repeating the PSA and doing another biopsy might be indicated in such patients, given the sensitivity of first biopsies, Dr. Li advised.

The researchers plan to expand their study so that it includes a greater number of patients, and future studies will include both retrospective and prospective data, they said.

"This is a very significant study," said Peng Lee, MD, PhD, associate professor of pathology and urology at the New York University School of Medicine in New York City. Dr. Lee specializes in research on prostate cancer. "Other than PSA, we don't have good biomarkers to guide clinicians in detecting prostate cancer. This study shows that PSA can provide guidance about which patients should undergo biopsy," Dr. Lee added.

Dr. Lee noted that prostate cancer might not have been found until the second or third biopsy on some patients in the study because of the limitations of the biopsy used. "Many clinicians are still doing a 12-core biopsy, but this study clearly suggests that there might be clinical utility in a core biopsy of more than 12 cores," he said. "That might result in a higher detection rate, rather than having patients get worried because they have a high PSA and then having to go through repeat biopsies."

"The trend now is to do biopsies of more than 12 cores, and I think that's a good trend," Dr. Lee added.

Dr. Lee agreed that the study should be extended to include more patients. A longer follow-up would also be helpful in assessing the significance of the study's findings, because many prostate cancers have indolent courses, Dr. Lee added. "If they had more patients and more cases, the study would be strengthened, but the findings are extremely important and very useful," Dr. Lee said.

Dr. Pincus, Dr. Li, and Dr. Lee have disclosed no relevant financial relationships.

American Society for Clinical Pathology (ASCP) 2010 Annual Meeting: Abstract 148. Presented October 29, 2010.

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