Men who get a "false-positive" prostate cancer result -- an abnormal screening test followed by a biopsy indicating no evidence of cancer -- appear more likely to worry about their subsequent risk of cancer and report more problems with sexual function compared to men with normal screening results, according to a University of Iowa study.

The study findings, based on telephone surveys of 210 men, appear in the February online issue of the journal Urology. Prostate cancer is the most common non-skin malignancy diagnosed in men in the United States. The majority of men in the United States are screened beginning at age 50 with the prostate-specific antigen (PSA) test.

"This study emphasizes the importance of doctors' discussing the pros and cons of prostate cancer screening with patients," said the study's lead author David Katz, M.D., associate professor of internal medicine in the UI Roy J. and Lucille A. Carver College of Medicine, and of epidemiology in the UI College of Public Health.

"Because screening affects a large number of men relative to those who are expected to benefit from treatment, even a small adverse effect of apparently false-positive results on cancer-related worry and quality of life could have a substantial impact on public health," said Katz, who also is a staff physician and researcher with the Department of Veterans Affairs Iowa City Health Care System and its Center for Research in the Implementation of Innovative Strategies and Practices.

The study team interviewed 101 men who had normal PSA levels and 109 men who had an abnormal PSA reading or abnormal digital rectal examination, but whose biopsy for prostate cancer then was negative.

Men with false-positives were about three times as likely to report being at least somewhat worried about getting prostate cancer and nearly twice as likely to report being bothered by their sexual function.

Katz said that the increased problems with sexual function reported by men with false-positives could be a residual effect of the biopsy, which can cause short-term pain or other side effects, or it could be an effect from worry about the possibility of still having cancer. "This finding warrants further investigation," he said.

"Men's perceptions following a false-positive prostate screening test are parallel to those of women who have an abnormal mammography exam but whose follow-up biopsy shows no breast cancer," Katz said. "It's understandable that false-positive prostate exams could affect men's outlook on their health."

As with other prostate cancer screening studies, the UI-led study raises the question whether men without any prostate cancer symptoms should receive PSA testing.

Katz said that given the lack of definitive evidence that PSA screening saves lives in asymptomatic men, deciding whether to have a PSA screening test needs to be an individualized decision that considers the patient's current health status and risk factors, such as being African-American and/or having a family history of the disease.

"Men can discuss the pros and cons of getting a PSA test with their doctors. However, once a man decides to go ahead and get a PSA test, if its results are abnormal, he typically should have ongoing follow-up and surveillance for prostate cancer," Katz said.

Katz said that a strength of the UI study was that it did not rely on volunteers. "Volunteers who sign up for a prostate cancer screening study represent a different type of population than that comprised by the individuals in our study, who were patients seen in the usual course of care," he said.

However, Katz noted, a limitation of the study is that the researchers were not able to obtain baseline data on how the men originally felt about their health prior to screening. In addition, the study focused primarily on Caucasian men.

The study was funded in part by a Preventive Oncology Academic Award from the National Cancer Institute, with supplemental support from the University of Wisconsin Comprehensive Cancer Center.

Katz also is a member of the Holden Comprehensive Cancer Center at the UI. In addition to Katz, the study involved researchers from the University of Wisconsin, Indiana University, and Veterans Affairs Health Services Research and Development in Indianapolis.