Research Explores Biopsy and MRI Procedures
Thanks to advancements in technology, a patient with an elevated PSA could have a choice to make regarding his next steps. However, there are pros and cons to the various scan and biopsy options that may be available. When a patient has an elevated PSA, his physician will typically recommend undergoing a biopsy to check for prostate cancer. This needle biopsy withdraws small samples, or cores, from the prostate that are checked for cancer cells under a microscope. Sometimes the patient will first have a multiparametric MRI scan to help determine if a biopsy is necessary.
Recently, a significant amount of research-and debate-has focused on comparing the efficacy and safety of various biopsy procedures, both with and without MRI scans.
The standard biopsy is a trans-rectal ultrasound (TRUS) guided biopsy, sometimes called a systematic biopsy, during which the doctor will use an ultrasound probe to guide the biopsy needle through a rectal probe and into the prostate gland to take the samples. Typically, the doctor will take 12 samples with a TRUS-guided biopsy. A major concern with a standard biopsy is that cancer cells can be missed.
A newer option is an MRI-guided targeted biopsy. With this method, the patient will first have a multiparametric MRI scan of the prostate, and the biopsy will take samples only from the areas of the prostate that appear suspicious for cancer, according to the MRI results. This type of a biopsy is sometimes called a fusion biopsy because the rectal ultrasound image is matched, or fused, with the MRI scan images in real time.
Another option is a trans-perineal biopsy, which can be a template mapping biopsy or a targeted biopsy. With a trans-perineal biopsy, the doctor will insert the biopsy needle through the patch of skin behind the testicles, called the perineum. Trans-perineal template prostate mapping biopsies use an ultrasound to create a threedimensional map of the whole prostate. Then, the prostate is divided into 24 areas and during the biopsy at least one sample is taken from each of these sections.
The following sections summarize some recent research in these areas.
MRI-Guided Biopsies Improve Accuracy
The PRECISION trial included 500 men with elevated PSAs who were randomized to one of two groups: having a standard biopsy without an MRI or having an MRI-targeted biopsy. Twenty-eight percent of the men in the MRI group had scan results that did not reveal signs of cancer, so they did not have any biopsies. The rest of the men in the MRI group underwent a targeted biopsies because their scans were suggestive of cancer.
MRI-targeted biopsies revealed clinically significant cancer in 38% of the men, compared to 26% in the standard biopsy group. Fewer men in the MRI-targeted biopsy group were diagnosed with clinically insignificant cancer, indicating that the MRItargeted biopsy was more accurate at detecting potentially harmful cancers.
N Engl J Med. 2018 May 10;378(19):1767-1777. doi: 10.1056/NEJMoa1801993. Epub 2018 Mar 18.
Combining Targeted and Systematic Biopsies
Two recent trials compared standard and targeted biopsies and found that combining the two methods offered the best chance of detecting prostate cancer.
The MRI-FIRST trial included 250 patients. Overall, 37% of the patients had clinically significant prostate cancer, and 66% of these cancers were detected by both systematic and targeted biopsies. However, targeted biopsies only found 20% of these cancers, and systematic biopsies only found 14%. This means that about 5% of the cancers would have been missed without a systematic biopsy, and 7% without a targeted biopsy. The authors concluded their data supports a need for both targeted and systematic biopsies.
For the 248 men in the PAIREDCAP study, the overall rate of cancer detection was 70% when combining standard and targeted biopsy. The targeted biopsy rate was slightly more sensitive than the systematic biopsy rate, but combining the two approaches detected 11% to 33% more cancers than either method alone.
Lancet Oncol. 2019 Jan;20(1):100-109. doi: 10.1016/ S1470-2045(18)30569-2. Epub 2018 Nov 21.
JAMA Surg. 2019 Jun 12. doi: 10.1001/ jamasurg.2019.1734.
The PICTURE Study: Adverse Events with Trans-perineal Template Prostate Mapping Biopsies
This study of 249 patients found that 94.8% of patients reported adverse events. Only a small percent (3.2%) were serious. The authors concluded that trans-perineal template prostate mapping biopsies cause high rates of urinary retention and a detrimental impact on both urinary and sexual functions, and patients should be counseled accordingly. Increased use of multiparametric MRI and targeted biopsies could minimize the harms of transperineal template prostate mapping biopsies.
J Urol. 2018 Dec;200(6):1235-1240. doi: 10.1016/j.juro.2018.06.033. Epub 2018 Jun 27.
Dr. Catalona’s Opinion
In an ideal world, a urologist would have an MRI scan on all men undergoing prostate biopsy. However, these scans are expensive and many insurance companies will not cover them unless the patient has already had a prostate biopsy that did not show cancer and still has a rising PSA level. MRI scans are not perfect, and some scans fail to show regions of the prostate that contain potentially life-threatening prostate cancers, and some regions that look like serious prostate cancer on the MRI scan turn out to be patches of inflammation or benign prostatic enlargement. There is increasing recent interest in trans-perineal biopsies in which the path of the biopsy needle does not enter the rectum. More information is needed to fully evaluate them.