THURSDAY, March 24, 2005 (HealthDay News) -- A combination of both the blood PSA test and the digital rectal exam appears to work best for detecting prostate cancer, according to early results from an ongoing study.
The study is part of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial being conducted by researchers at Washington University School of Medicine in St. Louis and several other institutions.
Overall, about 14 percent of men screened so far in the study tested positive for signs of prostate cancer. According to the researchers, eight percent of men tested positive on the PSA test, while positive findings were uncovered in seven percent of men via the digital rectal exam.
Because only one percent of men had a positive result on both screeening methods, the researchers say the findings support a continued need for both methods.
"We were hopeful some years ago that men could just have the PSA blood test, because men hate the rectal exam," Dr. Gerald L. Andriole Jr., head of the division of urologic surgery at Washington University and Barnes-Jewish Hospital, said in a prepared statement. "We've found that if you omit the digital rectal exam, you'll miss a certain percentage of cancers."
The study will continue until 2019 and should enable researchers to determine whether current prostate screening practices do reduce death from the disease.
A number of factors influence current uncertainty about prostate cancer screening. Both the prostate-specific antigen (PSA) blood test and the rectal exam can be inaccurate, providing both false negatives and false positives, and neither test reveals how aggressive a particular prostate cancer might be.
In addition, prostate cancer often grows very slowly, while treatments may have unpleasant side effects. That means that, especially in older men, leaving the prostate cancer alone may often be preferable to treating it.
"But the main thing is we don't know whether screening saves lives. Our study follows about 75,000 men, half of whom we are screening, and half of whom are getting conventional care. By comparing groups over the long term, we will see what difference screening makes in survival rates," Andriole said.
The results appear in two papers, one in the March 16 issue of the Journal of the National Cancer Institute and the other in the March issue of the Journal of Urology.
The U.S. National Cancer Institute has more about prostate cancer screening.