ORLANDO—New findings from a large prostate cancer (PCa) screening study suggest that men with an initial screening PSA value below 1.0 ng/mL may be able to wait longer than those with higher values before having another PSA test. In addition, data support lowering the PSA threshold for prostate biopsy from 4.0 to 3.0.

In the study of 42,376 men aged 55-74 years in Rotterdam, the Netherlands, investigators found that few men who had first-time PSA levels below 3.0 developed PCa and died from the disease. Within this group of men, the higher the initial PSA level, the greater the risk of being diagnosed with PCa and more aggressive disease and the greater the risk of dying from PCa.

Compared with men who had an initial PSA below 1.0, the overall risk of a PCa diagnosis increased fourfold and 10.3-fold for those with initial PSA values of 1.0-1.9 and 2.0-2.9, respectively. The risk increased 2.7-fold and 6.2-fold for aggressive PCa and 4.0-fold and 7.6 fold for PCa mortality.

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Study findings were announced at a press conference held prior to the start of the fourth annual Genitourinary Cancers Symposium. Senior investigator Monique Roobol, PhD, an epidemiologist in the Department of Urology at Erasmus University Medical Center in Rotterdam, presented the findings.

The favorable outcomes in men with initial PSA values below 1.0 (45% of men in the study) supports prolongation of screening intervals, for example, up to eight years, Dr. Roobol told listeners.

“These results can contribute to better individual management of men in PSA-based screening programs,” she said.

“Our results strengthen the justification of the use of PSA in risk stratification for screening purposes,” said lead researcher Meelan Bul, MD, a doctoral candidate at Erasmus. “This means that we can possibly avoid unnecessary testing, diagnosis, and treatment of less aggressive disease, with the accompanying side effects, by focusing biopsies and other follow-up on men with higher initial PSAs above 3.0.”

“I believe this study gives us some confidence that annual PSA screening is going to soon become a thing of the past,” said Nicholas J. Vogelzang, MD, who moderated the press conference. Men with low PSA values, particularly those with values less than 1.0 and probably less than 2.0 “certainly could be considered for substantially longer intervals of PSA screening,” said Dr. Vogelzang, Chair and Medical Director of the Development Therapeutics Committee of US Oncology Research and Clinical Professor of Medicine at the University of Nevada School of Medicine in Las Vegas.

The data suggest that the traditional 4.0 threshold for prostate biopsy should drop to 3.0, he added.

The study is part of the larger European Randomized Study of Screening for Prostate Cancer. Participants were randomized to either screening or a control arm. Of the 42,376 men, 19,950 were initially screened and biopsies were recommended for those with PSA levels of 3.0 or higher, with four-year screening intervals. The median follow-up was 11 years.

A total of 15,758 subjects (79%) had an initial PSA level below 3.0. Between 1993 and 2008, 915 (5.8%) of these men were diagnosed with PCa and 23 (0.14%) died from the disease (five with screen-detected and 18 with interval-detected cancer). Of the 915 men, 182 had their cancers detected between screenings. This frequently indicated a faster-moving disease, according to researchers.

Overall, 169 men (1.1%) had aggressive PCa, defined as clinical stage greater than T2c, Gleason score greater than 8, a PSA level greater than 20.0, positive lymph nodes, or metastases at diagnosis.

Only 129 (1.8%) of the 7,126 men with PSA scores below 1.0 were eventually diagnosed with PCa and only three died from the malignancy (0.04%). Of the 129 PCa cases, 31 (0.4%) were considered to be aggressive.

Of the 6,156 subjects with PSA levels of 1.0-1.9, PCa developed in 415 (6.7%), aggressive PCa developed in 72 (1.2%), and 11 died from the cancer (0.18%). Among the 2,476 men with PSA levels of 2.0-2.9, PCa was diagnosed in 371 (15.0%), aggressive PCa was diagnosed in 66 (2.7%), and nine died from the disease (0.36%).

The symposium is co-sponsored by the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.