There has been much debate regarding the utility of prostate cancer screening in reducing the rates of deaths due to this cancer among men. While the ERSPC (European Randomized Study of Screening for Prostate Cancer) suggests that screening reduced prostate cancer deaths, the PLCO (Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial) found that regular screening does not reduce the cancer death rates in prostate cancer. Researchers thus looked at the actual picture as to which of these – ERSPC or PLCO are correct.
The results of this large analysis were published in the recent issue of Annals of Internal Medicine published yesterday 5th September 2017, in a study entitled, “Reconciling the Effects of Screening on Prostate Cancer Mortality in the ERSPC and PLCO Trials.”
Prostate cancers are typically slow growing and thus annual blood tests such as the prostate specific antigen (PSA) suggested for screening for prostate cancers has been controversial. Due to the differing opinions and studies showing that men with prostate cancers usually do not die of prostate cancers as they are so slow to grow, in 2012, the U.S. Preventive Services Task Force (USPSTF) issued a recommendation that most men ages 55 to 69—except for those who have a family history of the disease or are at high risk of developing the cancer—should not get PSA testing done at routine intervals.
Prostate cancer cells. Image Credit: royaltystockphoto.com / Shutterstock
This recommendation was based on the results of two large studies one each from Europe and USA. The U.S. study, the PLCO, did not show a reduction is death rates due to routine screening while the ERSPC showed a reduction in deaths due to routine screening. Both of these studies were published simultaneously in the New England Journal of Medicine.
To analyse the actual effects of screening on prostate cancer the researchers looked at the populations studied for both ERPC and PLCO and used complex statistical tools to assess the outcomes. They gathered data from all the randomized controlled trials in Europe and the United States including men aged 55 to 69 (in case of ERSPC population) or 55 to 74 (in case of PLCO population) years. All of these participants were divided into intervention and control groups. The intervention groups underwent prostate cancer screening while the controls did not. The incidence of new prostate cancers and survival rates for the same were assessed for the individuals.
For all the participants mean lead times to diagnosis of prostate cancer or MLT was calculated. Results showed that estimated MLT were same for both ERPC and PLCO populations but was slightly longer in the PLCO control group that did not undergo the screening. Screening rates were same for both studies and results showed that screening resulted in a 7% to 9% reduction in the risk for prostate cancer death per year of mean lead times. This means that there is a 25% to 31% and 27% to 32% lower risk for prostate cancer deaths when the men underwent screening in the ERSPC and PLCO groups, respectively.
Researchers concluded that both the ERSPC and PLCO results point to the fact that prostate cancer screening reducing the risk of deaths from it significantly. The study was funded by the National Cancer Institute.
Prostate cancer remains one of the most common cancers in men and is a typically slow growing cancer with most men not noticing the symptoms until the cancer has become large enough to press against the urethra and interfere with urination. As the tumour grows there are symptoms such as an increase in the frequency to urinate (particularly at night), a greater sense of urgency to reach a toilet, difficulty in starting and continuing to pass urine, a weak urine flow, and a feeling of incomplete emptying of the bladder.
The risk of developing prostate cancer increases with age and the condition usually develops in men aged 50 years or older. Individuals of Afro-Caribbean or African descent are at a greater risk of developing the cancer, while those of Asian descent are at less risk. In addition, men with a first-degree relative who has had prostate cancer are at a slightly increased risk for developing this cancer.
Usually, a diagnosis is made based on a physical examination of the prostate, blood tests and a biopsy. Physical examination includes a digital rectal examination or DRE. Blood is tested to check the level of a protein called prostate-specific antigen (PSA), raised levels of which may indicate prostate problems including early cancer.
Immediate treatment may not be necessary for many prostate cancers. This is called "watchful waiting" or "active surveillance" where the patient is monitored for cancer progression. Treatment includes surgical removal of the gland or prostatectomy, followed by radiotherapy to kill any remaining cancer cells. Prostatectomy and radiotherapy may be followed by hormone therapy, which reduces testosterone, which causes the cancer to grow. Individuals with advanced prostate cancer that has spread to other organs or who have not been responsive to hormonal therapy may be treated with chemotherapy.