ORLANDO—Men with PSA levels below 2 ng/mL can safely defer repeat testing to once every 2 years, and those with PSA levels less than 1 ng/mL can reduce re-tests to once every 5 years, according to data from the National Cancer Institute’s nationwide PLCO (Prostate, Lung, Colorectal, Ovarian) cancer screening trial.

E. David Crawford, MD, reported the PLCO data at the plenary session of the 38th Annual Meeting of the American Society of Clinical Oncology (abstract 4). Dr. Crawford is senior associate director of the University of Colorado’s Health Sciences Center, Denver.

The PLCO trial was started in 1993 to address the controversy of screening for a number of cancers; 154,000 men and women have been entered into this large trial, with ages of 55 to 74 years. "Prostate cancer screening is controversial, and one purpose of this trial is to evaluate the value (if any) of prostate cancer screening," Dr. Crawford said.

The goal of the PSA analysis was to estimate the risk that a subject’s normal baseline PSA level would rise above the normal limit (defined as 4 ng/mL) during years 1 through 5.

All men in the trial had PSA testing yearly for 6 years and digital rectal exam yearly for the first 4 years. Baseline PSA levels were less than 4 ng/mL in 92% of the men and less than 2 ng/mL in 55%. Dr. Crawford reported data on nearly 30,000 men who had baseline PSA levels of less than 4 ng/mL and at least one subsequent PSA exam. Exclusion criteria included use of finasteride(Drug information on finasteride) (Proscar) or history of prostate cancer.

Dr. Crawford reported that 98.4% of men with baseline PSA levels less than 1 ng/mL continued to have PSA levels less than 4 ng/mL for each of the next 5 years (see Table). Of men with baseline PSA levels of 1 to 2 ng/mL, 98.8% continued to have PSA less than 4 ng/mL the following year.

"We found that the vast majority of men whose initial PSA levels are very low do not need to worry that they would skyrocket within 1 year," Dr. Crawford said.

The implication of the findings is that men whose initial screening tests show PSA levels less than 1 ng/mL can safely wait 5 years for their next PSA test (if they choose to be tested), and those men with PSA levels between 1 ng/mL and 2 ng/mL can be tested every 2 years rather than every year.