Study finds that MRI is more sensitive than PSA test for detecting prostate cancer

A recent BMJ Oncology study screens the prevalence of prostate magnetic resonance imaging (MRI) lesions in men based on age rather than prostate-specific antigen (PSA) levels.

Study: Prevalence of MRI lesions in men responding to a GP-led invitation for a prostate health check: a prospective cohort study. Image Credit: Peackstock / Shutterstock.com

Background

In men, the prevalence of prostate cancer is relatively common, with one recent study reporting that prostate cancer is the second most common cause of cancer-related death among men in the United Kingdom. In fact, as compared to the United States, France, Italy, and Spain, the U.K. has high age-standardized prostate cancer-specific mortality. 

The European Randomized Screening study for Prostate Cancer proposed that systematic screening can significantly reduce the prevalence of prostate cancer mortality. However, the introduction of screening programs based on PSA and standard transrectal biopsy has been associated with overdiagnoses, which ultimately leads to unnecessary continued monitoring or overtreatment, both of which increase healthcare costs.

Although PSA and subsequent transrectal biopsy in the case of positive PSA is a widely accepted screening procedure, it is not an accurate method to assess prostate cancer. Consistent with this observation, the Cluster Randomized Trial evaluated more than 400,000 men in the U.K. and estimated similar all-cause mortality rates between screened men (PSA) and controls. 

One previous study reported that MRI can reduce unnecessary biopsies in men with increased PSA. Considering this observation, scientists previously explored whether age-defined MRI scans alone, irrespective of PSA, can be used to determine the prevalence of prostate cancer. 

The PROMIS study revealed that individuals with MRI lesions scoring four out of five were at a 50% increased risk of prostate cancer, whereas those with five out of five scores were at a 70% increased risk of prostate cancer. These findings indicate a positive association between histological score and prostate cancer incidence.

About the study

The ReIMAGINE prostate cancer screening study is a single-center cohort study designed to determine the possibility of developing a screening approach using PSA and MRI.

Participants of the current study were selected based on the response of general physician (GP) invitation. Here, men between the ages of 50 and 75 without a history of prostate cancer were selected and subsequently subjected to a PSA blood test and screening MRI (sMRI).

Two radiologists independently scored the MRI findings as positive or negative. Men with a positive sMRI or PSA density of at least 0.12 ng/mL were considered screen-positive. Screen-negative participants were excluded from the study. Screen-positive individuals were referred to the National Health Service (NHS) for further assessment for cancer.

Study findings

Of 2,096 men across eight GP practices invited for this study, 457 men responded. Notably, older men responded to the invitation to a greater extent than relatively younger men. A multivariable logistic regression revealed that, as compared to Black men, white men were more likely to respond to the invitation. 

Due to the limited availability of MRI, all eligible participants were not able to participate in the study, which led to a total of 303 men who were ultimately subjected to both screening tests. About 21% screened positive and were recommended to NHS for further assessment.

Moreover, one in six men had a screen-positive MRI, whereas one in twenty men tested positive for PSA density alone. Most men with a screen-positive MRI had PSA levels less than 3.0 ng/mL.

Additionally, fifteen out of twenty-five men with a positive MRI with clinically significant cancer had PSA levels less than 3.0 ng/mL. NHS assessments revealed that 9.6% of the screened men had clinically significant prostate cancer, while only 1% had clinically insignificant disease.

Limitations

The current study has some limitations, including its small sample size. Furthermore, because the scanning center was located in London, the study was limited for wider invitation spread. A better-advertised campaign would have increased the number of participants.

The current study began before the onset of the coronavirus disease 2019 (COVID-19) pandemic, which subsequently paused participant recruitment between April 2020 and August 2020, after which the process restarted. However, many individuals avoided visiting healthcare facilities due to the pandemic.

Conclusions

The current study revealed that two out of three men with a positive screening MRI had PSA levels lower than 3.0 ng/mL. These findings indicate that MRI can be used to screen for prostate cancer risk independent of the PSA test.

This MRI-based screening strategy could be used for primary assessment of prostate cancer. Since the PSA test is associated with certain limitations in accurately detecting men at risk for prostate cancer, this MRI method could be an effective alternative approach. 

In the future, the researchers emphasize the potential advantages of a community-based MRI delivery program using a mobile MRI scanner.

Written by

Dr. Priyom Bose

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.