Prostate biopsy is performed to find out whether there is prostate cancer in men with a high PSA (Prostate Specific Antigen) test in the blood or in whom a suspicious mass is detected in the prostate by imaging methods.
The classical approach in people with high PSA levels is to first perform an anal palpation and then an rectal prostate biopsy. A small portion of prostate cancers can be felt on palpation, and if there is a suspicious finding, a biopsy can be performed to diagnose it. Classical prostate biopsy is performed by taking random pieces (6-12 pieces) from various parts of the prostate by seeing the prostate but without seeing the tumor, with an ultrasound probe inserted through the rectum. These parts are then examined in pathology and both the presence of cancer is said and the growth rate of the tumor is evaluated with a grading called the Gleason (pronounced Glison) score. For this, the pathologist assigns a score ranging from 1 to 5, depending on the extent to which the tumor appears different from normal tissue. It then adds up the two most frequent points. Therefore, the Gleason score is given as binary values such as 4+3, 3+5, 4+5, and the sum of these values varies between 5-10 in practice. Gleason 5 indicates the slowest and Gleason 10 the fastest (aggressive) tumor type.
In prostate cancer, the Gleason score shows the grade (grade) of the tumor and gives an idea about the growth rate of the tumor and the possibility of metastasis. The extent of the tumor in the body is determined by the stage of the tumor and is revealed by imaging methods such as PET-CT, tomography and MRI. Like many other cancers, prostate cancer is divided into 4 stages; In stages 1 and 2, the tumor is limited to the prostate, in stage 3, the tumor has spread outside the prostate or to regional lymph nodes. In stage 4, there is distant metastasis (usually to the bones).
There are some problems with the classical diagnostic methods of prostate cancer:
- In other organs, such as the liver and lung, a “suspicious” mass is first detected using ultrasound, tomography, and MRI, and then diagnosed with an imaging-guided biopsy. However, tumor is not usually seen in the prostate, therefore, in patients with high suspicion of cancer (PSA high), the diagnosis is tried to be made with biopsies taken from the prostate blindly. The prostate is the only organ in our body that can be diagnosed with a “blind” biopsy.
2. About 1/3 of prostate cancers can be missed in blinded prostate biopsies. Also, in about 1/4 of the cases the Gleason score is found to be lower than it actually is, meaning the tumor may appear less aggressive than it is, resulting in delayed or absent treatment.
3. In many patients, the biopsy may appear normal even though the PSA is high. In this case, the biopsy is repeated in more quadrants, but again blindly. However, multiple biopsies repeated can lead to problems such as bleeding and infection. In some cases, the biopsy is not done through the anus, but from the area called the “perineum” between the anus and the penis. In this method, called saturation biopsy, multiple needle biopsies are performed through evenly spaced holes using a mold placed in the perineum. This method is superior to conventional blind biopsy in detecting cancer, but requires needle biopsy through multiple holes.
Modern biopsy methods in prostate cancer
While prostate cancer cannot normally be seen with radiological imaging methods, it has become possible to detect prostate cancer at an early stage for the first time with the developments in MRI in recent years. Especially in new MRI devices, the tumor can be detected early in approximately 80% of prostate cancer patients with a technique called “multiparametric MRI”. It is thought that cancers that Emar cannot show are more slowly progressing and less clinically important cancers. These tumors detected by MRI can then be biopsied “with imaging guidance” rather than “blindly”, and a more accurate diagnosis can be made with much less needle prickling. Imaging-guided prostate biopsy can be performed directly on the MRI device, or it can be performed on ultrasound devices by combining MRI images with ultrasound images (fusion imaging).
The ability of MRI to show prostate cancer at an early stage has dramatically changed both the diagnosis and treatment methods of prostate cancer. Today, classical approaches are still applied in many centers around the world. However, in many developed centers, blind rectal biopsy in prostate cancer has been abandoned. In these centers, a multiparametric MRI is performed first in patients with high PSA and if a suspicious mass is detected, biopsy is performed with imaging rather than blinding. If the MRI is normal, the patient is followed up routinely and the MRI is repeated at regular intervals.