MedicalResearch.com Interview with:
Professor of Clinical Epidemiology
Head of Section, Clinical Epidemiology & Public Health
Population Health Sciences
Bristol Medical School
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Screening for prostate cancer using the PSA test aims to detect prostate cancer at an early stage, before symptoms develop, when treatment can be offered that may avoid the risks of advanced cancer or may extend life.
Evidence from a large European trial suggests that PSA screening at 2 to 4 yearly intervals could reduce prostate-cancer deaths by 20%. after 13 years of follow-up. However, there are problems with the accuracy of the PSA test and potential harmful consequences. In particular, using the PSA test to screen for prostate cancer results in some tested men being diagnosed with low-risk, harmless cancers that are unlikely to progress or require treatment. This problem may be particularly exacerbated when using repeated PSA testing as a screening strategy.
The CAP trial offered a one-off PSA test to men aged 50-69 years in the UK. The goal of this low-intensity, one-off PSA testing was to avoid unnecessary screening while still identifying men with high risk, aggressive cancers for whom screening and early detection can reduce morbidity and mortality. However, we found that after an average 10-years of follow-up, the PSA test still detected too many low-risk prostate cancers, while also missing cancers that did need treatment. After an average 10-years of follow-up, the group who had been screened had the same percentage of men dying from prostate cancer as those who had not been screened (0.29%).
MedicalResearch.com: What should readers take away from your report?
Response: The CAP trial adds to the evidence that screening men with PSA detects some disease that would be unlikely to cause any harm but also misses some aggressive prostate cancers that do need treatment. Overall, screening with a one-off PSA test does not save lives after an average 10 years follow-up after the disease is detected, but we must wait longer to see if it makes a difference at 15 and 20 years.
However, finding a way to improve the number of aggressive prostate cancers that get caught in time, whilst reducing the number of men who have screening, biopsies or treatments unnecessarily, remains important. Imaging before biopsy using MRI appears to help in detecting and targeting serious cancers.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Research is ongoing to evaluate new technologies that could pave the way for safe and effective screening policies in the future. Genetic tools may help to guide decisions of who to screen towards men at the highest risk of aggressive prostate cancer requiring treatment.
Mp MRI is a new test that uses a powerful magnetic field, radio frequency pulses and a computer to provide a detailed image of the prostate to aid the detection and targeting of clinically significant prostate cancer at biopsy. Performing an MRI scan before prostate biopsy could reduce the number of men with low-risk disease who undergo unnecessary biopsy and treatment while improving the diagnosis of aggressive disease that requires treatment.
Evaluating the risk of prostate cancer such as a strong family history and additional blood tests to predict future risk of prostate cancer or to screen for the presence of early disease are under investigation to improve the detection of prostate cancers requiring treatment.
Disclosures: The study was funded by Cancer Research UK and the UK National Institute for Health Research.
Martin RM, Donovan JL, Turner EL, Metcalfe C, Young GJ, Walsh EI, Lane JA, Noble S, Oliver SE, Evans S, Sterne JAC, Holding P, Ben-Shlomo Y, Brindle P, Williams NJ, Hill EM, Ng SY, Toole J, Tazewell MK, Hughes LJ, Davies CF, Thorn JC, Down E, Davey Smith G, Neal DE, Hamdy FC, . Effect of a Low-Intensity PSA-Based Screening Intervention on Prostate Cancer MortalityThe CAP Randomized Clinical Trial. JAMA.2018;319(9):883–895. doi:10.1001/jama.2018.0154
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