Prostate cancer is one of the most common cancers in men in the US, with approximately 1 in 8 men being diagnosed during their lifetime and the incidence rate continuing to increase by about 3 percent every year. If caught early, the outlook for an individual diagnosed with prostate cancer is good - data from the CDC shows a 100 percent 5-year survival rate in those diagnosed at the earliest stage - however, if diagnosed at a later stage, when the cancer has spread, 5-year survival decreases to 36.2 percent. This emphasizes the importance of early diagnosis and screening for an improved chance of survival.
This article will explain what mpMRI scans are and how they can be used to improve prostate cancer diagnostic accuracy and decrease the number of unnecessary prostate biopsies.
Traditional methods of detecting prostate cancer are limited in their accuracy and have high false positive rates, which can lead to unnecessary biopsies. These also lack the ability to distinguish between aggressive and slow-growing cancers. MRI scans are increasingly being used as a more accurate screening tool, removing the need for unnecessary prostate biopsies.
Traditional methods of diagnosing prostate cancer include the prostate-specific antigen (PSA) test. Normal and cancerous cells in the prostate gland produce PSA, and its levels can be detected in the blood. As PSA levels increase, the chance of having prostate cancer increases, however, there is no specific cut-off higher than which a man will definitely have cancer.
A digital rectal exam (DRE) is another traditional method of diagnosing prostate cancer. It involves a medical professional inserting a gloved finger into the rectum to feel for bumps or hard areas that could be a tumor. Both of these methods have a high rate of false positives - 46.6 percent for the PSA test, 41 percent for DRE, and 23.1 percent when a combination is used. These false positives will lead to unnecessary biopsies.
Biopsies are used to diagnose prostate cancer following a high PSA test and/or irregularities detected during a DRE. They require the insertion of a needle either through the wall of the rectum or through the perineum (the skin between the scrotum and anus) to reach the prostate. Biopsies can show for certain whether cancer is present in the prostate and can determine how aggressive the cancer might be. However, cancer may be missed in a biopsy, as the cancer could be in a part of the prostate not sampled.
Prostate biopsies can be painful or uncomfortable, and short-term bleeding is common. Major rectal bleeding is uncommon (less than 1 percent) but is very serious when it does occur, requiring hospitalization and potentially a blood transfusion. It is also possible to get an infection and further urinary issues resulting from a biopsy. In rare cases (1.2 percent), a urinary tract infection may spread to the kidneys, resulting in sepsis. Men who have just undergone a prostate biopsy are over twice as likely to be hospitalized for infectious complications than controls. With these complications in mind, it is clear that unnecessary prostate biopsies should be avoided.
Multiparametric magnetic resonance imaging (mpMRI) is a method of creating a detailed 3D image of the prostate using a combination of imaging techniques. These techniques include:
An mpMRI can detect any suspicious masses within the prostate and, due to the 3D nature of the image, it is possible to locate exactly where these are within the prostate. This technique can also determine the mass's size and shape. mpMRIs provide sufficient information to advise medical professionals whether a biopsy is necessary and exactly where to target the biopsy if required.
Traditional biopsies require taking a large number of samples to avoid missing sampling a cancerous area - this can be 25 or more samples. mpMRI-targeted biopsies require fewer (in one study, a 77 percent reduction) as only the area identified as suspicious from the MRI needs to be sampled. Using mpMRI methods increases the accuracy of diagnosing prostate cancer by 57 percent.
In addition, the use of mpMRI decreases the detection of slow-growing or non-aggressive prostate cancer - which may not cause any symptoms or problems, and so the detection of which serves only to worry individuals unnecessarily. Finally, mpMRIs also lower the number of men requiring biopsies.
MRI scans can improve diagnostic accuracy by up to 57 percent. They produce such a detailed image of any tumors within the prostate that they can distinguish between aggressive and non-aggressive cancers. mpMRI utilizes different imaging techniques to assess increased tissue stiffness—characteristic of more aggressive tumors—and blood flow patterns, which appear abnormal and increase in aggressive tumors to support their rapid growth. The ability to distinguish between aggressive and non-aggressive cancers allows for a reduction in unnecessary biopsies and interventions.
mpMRI scans can prevent false positives produced from tests such as PSA tests and DRE, distinguish significant cancers from slow-growing, non-aggressive cancers, and reduce the need for unnecessary biopsies. They can, therefore, provide men with more peace of mind by delivering clear and accurate results and by reducing the need for invasive procedures unless absolutely necessary.
Clinical studies, including the PRECISE trial, have demonstrated the effectiveness of mpMRI in reducing unnecessary biopsies. Major health organizations, such as the American Urological Association and the European Association of Urology, now recommend the use of mpMRI before initial prostate biopsy. These updated guidelines have led to mpMRI increasingly being used as part of the prostate cancer diagnostic pathway, particularly when men present with elevated PSA but no other symptoms.
Though now recommended as part of prostate cancer diagnosis, MRI scans are not available everywhere. This makes it difficult for some patients to access this important diagnostic tool, particularly those living in rural and remote areas where long travel times are required to access healthcare facilities offering this service. In addition, widespread use may be limited by the cost of an MRI, which, though cost-effective, is fairly expensive - especially compared to the PSA test.
Skilled radiologists who have undergone extensive training are required to use and interpret mpMRI scans. This expertise is particularly important for maintaining diagnostic accuracy. Not all healthcare providers will have sufficient expertise or the high-quality equipment required, further limiting access to mpMRIs.
mpMRIs are becoming a key part of the diagnosis process for prostate cancer. Traditional methods, such as the PSA test, have high false positive rates, leading to large numbers of men having unnecessary biopsies. Biopsies are an important tool. However, they are often painful and can lead to severe and dangerous complications - so it is important to avoid them unless necessary. Incorporating mpMRIs into the diagnostic path - as recommended by major health organizations - reduces the number of unnecessary biopsies and improves the accuracy of biopsies (if required) by providing an exact location to target. Challenges such as lack of accessibility, high costs, and requirement for expertise can limit the availability of this important diagnostic tool.
If you want to be proactive about your health, why not book an Ezra full-body MRI? Our annual scan catches potential cancer - including prostate cancer - earlier, leveraging AI through the screening process to make it more efficient, affordable, and faster.
