SAN FRANCISCO — Men whose prostate-specific antigen levels were less than 3 ng/mL at their initial screenings had a 20-fold lower risk of dying of prostate cancer, compared with men who presented with higher PSA levels in a study that tracked 19,970 men for 12 years.
The 15,582 men who initially presented with PSA levels less than 3 ng/mL and a normal digital rectal exam did not undergo biopsy, Dr. Monique J. Roobol told a symposium on genitourinary cancers.
Biopsy was offered to men with higher screening PSA levels or positive digital rectal exams in the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer. Rescreening was offered after 1, 4, and 8 years. The analysis included all prostate cancers detected at or between screenings.
Of men biopsied because of screening PSA levels of 3 ng/mL or greater, 1% died of prostate cancer. In the group with initial PSA levels less than 3 ng/mL, 700 prostate cancers were subsequently detected, but only eight men (0.05%) died of the disease. To prevent one prostate cancer death, 1,981 men with initial PSA levels less than 3 ng/mL need to be biopsied, an unacceptable rate, said Dr. Roobol of the urology department at Erasmus University, Rotterdam, the Netherlands.
Mounting evidence suggests prostate cancer in men with low PSA levels may be indolent disease with better outcomes than cancer detected in men with higher PSA levels, the researchers said.
New risk markers need to be developed if the few prostate cancer deaths in men with screening PSA levels less than 3 ng/mL are to be prevented, said Dr. Roobol at the symposium, sponsored by the American Society of Clinical Oncology, the American Society for Therapeutic Radiology and Oncology, and the Society of Urologic Oncology. None of 139 men who presented with a PSA level less than 1 ng/mL died of prostate cancer.
Three of the eight men in the no-initial-biopsy group who died of prostate cancer were diagnosed with the disease within a year of initial screening; in two of the three, the PSA level did not change between screening and diagnosis. The other five in the no-initial-biopsy group who died of prostate cancer were diagnosed 2–8 years after initial screening. The time from diagnosis to death for these men ranged from 6 months to 8 years.