On 5th May, the New England Journal of Medicine released a correspondence report that reevaluated a PSA test on Prostate, Lung, Colorectal and Ovarian (PLCO) trials and the Randomized Study of Screening for Prostate Cancer (ERSPC). The objective of the evaluation, sponsored by the National Cancer Institute of America, was to help reduce the deaths resulted by prostate cancer.
The original focus of the study was to find out the reality about mortality rate in men who performed early screening for the diagnosis of prostate cancer through PSA.
These were the two largest randomized trials that have been conducted in the US and in Europe with the sole objective to resolve the controversy surrounding the PSA test.
The trials were conducted with screening groups of 1,000 men, aged 55 to 69 years, all of whom received PSA test screening every 1 to 4 years for a decade. However, instead of taking the PSA test, the men from the control group only underwent regular checkups.
The resulting figures obtained from the screened group participants and control group participants gave a fair result compared to the study. The aftermath of the findings was quite intriguing as the results collected from the US and different European countries produced contrasting tallies.
The results of PLCO trials from the screened group recorded 158 deaths out of 38,340 total participants while from the control group, 145 deaths were recorded out of 38,345 total participants. The risk ratio was found to be 1.09 which favored the control group.
The ERSPC trials were conducted in the following seven European countries.
- In Sweden, 39 deaths out of 5,901 total participants were recorded in the screened group, 70 deaths out of 5,951 total participants were recorded in control group. The risk ratio was found to be 0.56 which strongly favored screening.
- In Belgium, 22 deaths were recorded out of 4,307 total participants in the screened group and 25 deaths out of 4,255 total participants in control group. The risk ratio was found out to be 0.86 which favored screening.
- In Netherlands, 69 deaths out of 17,443 total participants were recorded in the screened group and 97 deaths out of 17,390 total participants were recorded in control group. The risk ratio was found to be 0.71 which favored screening.
- In Italy, 19 deaths out of 7,266 total participants in the screened were recorded and 22 deaths out of 7,251 total participants were recorded in control group. The risk factor was found to be 0.86 which favored screening.
- In Finland, 139 deaths out of 31,970 total participants were recorded in the screened group and 237 deaths out of 48,409 total participants were recorded in the control group. The risk group was found out to be 0.89 which favored screening.
- In Spain, 2 deaths out of 1,056 total participants were recorded in the screened group and 1 death out of 1,141 total participants was recorded in the control group. The risk ratio was 2.15 which favored control group, which was an anomalous result in the findings of European countries.
- In Switzerland, 9 deaths out of 4,948 total participants were recorded in screened group and 10 deaths out of 4,955 total participants were recorded in the control group. The risk ratio was found out to be 0.89 which favored screening.
From these elaborated results, the findings are not statistically coherent in across all countries. This discrepancy can act as hindrance in deciding if PSA screening should be recommended or discontinued.
Majority of times, the high levels of PSA are due to the presence of benign tumors or slowly progressing tumors that do not cause any harm in a life time. Furthermore, the high PSA levels can be due to other conditions such as prostate inflammation or prostate enlargement, instead of prostate cancer. It was also recorded that the cutoff range may not be uniform across ethnicities and extensive work has to be done in identifying cutoff range of PSA levels for different ethnicities.
In 10-12% cases of the PLCO trial, the diagnosis was false positive which normally leads to psychological stress over being diagnosed with cancer. While the patients worry about their condition, they opt for invasive treatment procedures such as biopsies only to find out that the condition was over diagnosed and did not require such extensive treatment. At other times, repeated PSA may be required to give accurate and updated results on the condition (depending on the age), but people may find themselves to be safe after a test or two which may lead to false negative results.
The PSA (prostate specific antigen) blood test is one of the screening procedures for early detection of prostate cancer that detects the PSA levels in the bloodstream. The PSA test was approved by the FDA in 1986, primarily to check the progression of prostate cancer in patients who have previously been diagnosed by the disease. However, it was only in 1994 when the FDA approved the PSA test to be conducted in conjunction with DRE (digital rectal examination), for asymptomatic cases of prostate cancer.
The working principal of PSA test governs by measuring the levels of prostate specific antigen present in the bloodstream; the normal levels are 4.0 ng/mL or less; while values exceeding 4.0ng/mL have been attributed to an ailment. Higher PSA levels were initially linked to prostate cancer. But, clinical trial researches have shown that high PSA levels do not always mean that a person is or will suffer from prostate cancer.
According to American Cancer Society, 1 in every 7 men in the US will be diagnosed with prostate cancer in a lifetime. 180,890 new cases are reported per annum, while 26,120 deaths per annum are recorded from prostate cancer, in the US alone.
It is to be noted that the PSA screening tests need to be improved in order to get better diagnosis that could also translate into better treatment and in turn a reduced mortality rate. The debate over PSA may continue till scientists come forward with solutions that can overcome the present limitations.
In last few years, the PSA test has been a popular screening method amongst doctors as well as patients. But now, the efficacy of PSA test will be questioned by many health experts. The US Preventive Services Task Force is midway to completing its recommendation report about the screening of prostate cancer.