The US Prostate Cancer Screening: 13 Years of Trial and How It Went Wrong
In the early 90’s, the American Prostate, Lung, Colorectal, and Ovarian Cancer Screening (PLCO) Trial was launched to study prostate-specific antigen (PSA) in men. The study tested 76,000 men, initially divided into two groups, the screening group and the control group. Those who are part of the screening group received yearly tests for 6 years, including 4 digital rectal exams. Those who are part of the control group received no type of tests. The long-term study’s goal was to determine the effects of screening on cancer-related mortality. However, the study was concluded as uninterpretable.
PSA testing is used to measure levels of protein produced by the prostate gland. Doctors use a blood sample to test for PSA levels to determine possible diseases. Studies show that men normally have low levels of PSA, and increased levels would suggest benign or prostate cancer. However, doctors don’t rely on the test alone; a clinical diagnosis is still a must to decide if further tests are needed.
PLCO Trial and PSA Testing
The PLCO Trial was designed for long-term study. In the middle of the study, PSA testing became popular in the U.S. and subjects were affected. Researchers found that more than half of the control group underwent at least 1 PSA test. They referred to this incident as an “opportunistic testing”. Members of their controlled group are no longer PSA-test free, resulting in a contaminated data. Researchers could not pinpoint any significant conclusion to their objective.
However, PLCO Trial continued and researchers went on with the study. They found out that PSA testing leads to over diagnosis of prostate cancer. During the 13 years of trial, 4,250 in the screening group were diagnosed with prostate cancer while there were 3,815 in the control group. With this data, researchers are questioning whether screening actually increases risk of death.
In conclusion, during the trial period, the rate of death to prostate cancer was low and showed no significant difference between the two groups. Their data was also flawed because of the fact that half of the controlled group experienced PSA testing when they weren’t supposed to. Doctors still recommend that men take other tests like biopsies and go through monitoring processes, not relying solely on PSA test results when testing for prostate cancer.