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Prostate biopsy

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A procedure in which hollow needle-core samples are removed from the  prostate gland to be examined pathologically.

 

It is typically performed when PSA blood test result is high. 

 

It may also be considered after a digital rectal exam (DRE) finds an abnormality. 

 

The most frequent side effect of the procedure is blood in the urine (31%).

 

Other side effects of prostate biopsy include infection (0.9%) and death (0.2%).

 

The procedure may be performed transrectally, through the urethra or through the perineum. 

 

The most common approach is transrectally, with the use of transrectal ultrasound: TRUS biopsy.

 

Extended biopsy protocols take 12-14 cores from the prostate gland through a thin needle in a systematic fashion from different regions of the prostate.

 

In template prostate mapping (TPM) or transperineal template-guided mapping biopsy (TTMB), typically 50 to 60 samples are taken of the prostate through a template with holes every 5mm, usually under a general or spinal anaesthesia.

 

Antibiotics are usually prescribed to minimize the risk of infection.

 

An enema may also be prescribed for the morning of the procedure. 

 

In the transrectal procedure, an ultrasound probe is inserted into the rectum to help guide the biopsy needles. 

 

A local anesthetic is administered into the tissue around the prostate, and spring-loaded prostate tissue biopsy needle is then inserted into the prostate.

 

PTRUS biopsy is a blind process since prostate cancer cannot be seen on ultrasound due to poor soft tissue resolution. 

 

Multi-parametric magnetic resonance imaging (mpMRI) can be used to better identify and characterize prostate cancer.

 

Many prostate cancers missed by conventional biopsy are detectable by MRI-guided targeted biopsy.

 

MRI-guided biopsy improved detection of significant prostate cancer by 17.7%, and decreased the diagnosis of insignificant or low-risk disease by 89.4% in a study.

 

When MRI is utilized to guide prostate biopsy, it is done by an interventional radiologist. 

 

A fusion MRI-US prostate biopsy:, a prostate MRI is performed before biopsy and then, at the time of biopsy, the MRI images are fused to the ultrasound images to guide the urologist to the suspicious targets. 

 

MRI-guided prostate biopsy is superior to standard TRUS-biopsy in prostate cancer detection. 

Screening for prostate cancer with PSA and MRI with subsequent combined biopsies for prostate cancer has a high probability to be more cost-effective compared with PSA screening using standard biopsy.

 

Side effects of biopsy include:

 

rectal pain or discomfort 

 

burning when passing urine

 

bruising 

 

bloody urine for 2-3 days 

 

bloody semen

 

poor erections 

 

infection of skin or urine 

 

infection of skin or urine requiring hospitalisation and intravenous antibiotics 

 

difficulty urinating 

 

The tissue samples are then examined under a microscope to determine whether cancer cells are present, and to evaluate the microscopic features, or Gleason score, of any cancer found. 

 

Tissue samples can be stained for the presence of PSA and other tumor markers in order to determine the origin of malignant cells that have metastasized.

 

MRI with targeted and standard biopsy in men with MRI results suggestive of prostate cancer was non-inferior to standard biopsy for detecting clinical significant prostate cancer and resulted in less detection of clinically insignificant cancer (STHLM3 consortium).

Large randomized trials have shown that PSA screening significantly reduces the risk of death from prostate cancer. 

PSA screening incurs substantial harms, however, most importantly overdiagnosis. 

Overdiagnosis refers to the diagnosis of a disease that would not have been diagnosed without screening. 

Prostate cancer overdiagnosis is associated with significant complications associated with treatment.

To lower the incidence of prostate cancer over diagnosis patients should undergo a triage process in patients with an elevated PSA before proceeding to prostate biopsy.

The cumulative percentage of false positive PSA results is between 10 and 15% with approximately 5% risk of falls positive screen with a subsequent negative biopsy.
The major with biopsy of the prostate is infection, which occurs in 5 to 7% of patients, and can result in hospitalization in 1 to 3%.
The complications to prostate biopsy include hematuria, less than 1%, rectal bleeding, urinary obstruction or retention, transient erectile dysfunction and substantial discomfort.

MRI testing permits targeted biopsy for individual lesions.

MRI guided biopsies can detect fewer clinically insignificant cancers, and more clinically significant cancers than systematic biopsies.

Significant prostate cancer is manifest with a Gleason score of six or above and more clinically significant cancers are seven and above.

Targeted biopsies can lead to an underestimated tumor risk and should not be used without the additional use of systematic biopsy.

In a randomized trial of MRI targeted biopsy for suspicious lesions or systematic biopsy plus MRI targeted biopsy for suspicious lesions: Found that omitting systemic biopsy halved the probability of detection of clinically insignificant cancers, but one in five clinically significant cancers was missed.

In the above GOTEBORG-2 trial, clinically significant cancers that were found only by means of systematic biopsy were of intermediate risk and most of low volume.

The use of MRI directed targeted biopsy for screening in early detection in patients with elevated PSA levels reduces the risk of over diagnosis by half the cost of delaying detection of intermediate risk tumors in a small proportion of patients (GOTEBORG-2 trial investigators)

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