Improving Prostate Cancer Detection Using MRI-Targeted TRUS-Guided Biopsy

Accurately diagnosing clinically significant prostate cancer at a time when the benefits of treatment outweigh the harm continues to elude clinicians because of the complex nature of prostate cancer. When patients are found to have a high prostate specific antigen (PSA) blood test, an abnormal digital rectal exam, or they have prostate cancer but are delaying treatment (active surveillance), they are referred for transrectal ultrasound (TRUS) guided biopsy. The sensitivity of TRUS with 12-core biopsies is only 53-68% so cancers can be missed, particularly in the anterior region of the prostate. In some cases, TRUS can be used to rule out other causes of abnormal test findings, however the specificity of TRUS is also fairly poor making it difficult for a man to know for certain if he is cancer free. Unfortunately, biopsies also cause serious side effects including incontinence, bowel dysfunction, infection and pain. Increasing the number of cores taken during biopsy does not typically translate to better detection rates.

Magnetic resonance imaging (MRI) has much greater resolution than TRUS and can therefore, detect changes in the prostate more accurately. If conducted prior to a targeted biopsy, MRI can also reduce the number of cores taken compared to a standard biopsy (e.g. 2-4 cores vs. 12 cores), which could reduce biopsy side effects while simultaneously increasing detection of clinically significant cancer compared to routine 12-core biopsies and saving health care system dollars. Technology that combines MRI at the same time as biopsy (MRI-TRUS fusion biopsy) is increasingly being used, with some promising results. However, these techniques require expensive equipment and specially-trained personnel, and are more time-consuming and restrictive in when the procedure can occur. Utilizing MRI prior to a TRUS-guided biopsy could provide the same benefits in terms of cancer detection, but at a more reasonable cost and shorter wait-times as MRI alone can be done in a variety of settings and times.

If the results of this study demonstrate that MRI-targeted biopsy improves detection of clinically significant cancer over TRUS-guided biopsy alone, it would suggest that this protocol may be a more practical solution. Moreover, if the results show that MRI-targeted biopsy could reduce the number of cores taken without missing clinically significant cancers, the local biopsy protocol could be adjusted in the future to minimize unnecessary harm in these populations of men. In summary, this study will have practical merits in minimizing costs and patient morbidity associated with unnecessary prostate biopsies and treatments across Canada.

The primary objective of this study is to determine if using MRI can improve cancer detection by identifying potential cancer targets prior to TRUS-guided biopsy in populations that have previous inconclusive results from TRUS-guided biopsies.

The secondary objectives are to:

• Determine the sensitivity, specificity, positive and negative predictive value of MRI in predicting clinically significant prostate cancer
• Identify areas of the prostate that would benefit most from MRI
• Estimate Type 1 and Type II errors of using MRI-targeted biopsy samples compared to both MRI-targeted and standard 12-core.
• Estimate cost savings by using MRI-targeted biopsy samples only compared to both MRI-targeted and standard 12-core.
• Compare cost-effectiveness of using MRI prior to TRUS-guided biopsy compared to MRI-fusion biopsy used in other centers

This is a prospective, single institution randomized clinical controlled trial.. Participants will be randomized in a 1:1 ratio to one of the following groups:

• Control Group: TRUS-guided systematic 12-core biopsy (standard care)
• Experimental Group: prostate MRI later followed by systematic 12-core TRUS-guided biopsy + targeted biopsy of additional MRI-detected cores

Inclusion criteria

• Referred for an ultrasound-guided prostate biopsy
• Indication 1: Men without a history of prostate cancer referred to the PAC for a biopsy who have a history of 1 negative biopsy who are being referred for a follow-up biopsy
• Indication 2: Men who have a history of diagnosis of prostate cancer and are currently on active surveillance under the care of an oncologist who are referred to the PAC for a follow-up biopsy

Exclusion criteria

• Are unable to consent on their own behalf
• Less than 3 months since previous biopsy (to avoid inflammation and hemorrhage confounding MRI image)
• A history of treatment for prostate cancer (including surgery, chemotherapy or radiotherapy)
• Emergent/urgent biopsy referrals
• History of urinary tract infections or prostatitis in the last 3 months
• Contraindications to MRI:
• Ferromagnetic or otherwise non-MRI compatible aneurysm clips
• The presence of an implanted pacemaker or implanted defibrillator device
• Contraindication to receiving Gadolinium containing contrast for the which may include past or current kidney disease or injury or kidney transplant
• Severe claustrophobia