A prostate biopsy is the taking of tissue samples from the prostate gland and examining them under a microscope for cell differentiation. Cancerous cells are shaped and arranged differently than healthy cells. The more differentiated cancerous cells are from healthy cells, the more aggressive the cancer .
The purpose of a prostate biopsy is to determine if a male has prostate cancer . The prostate is a small gland that is part of the male reproductive system. It sits just below the bladder and in front of the rectum and is normally about the size of a walnut. When enlarged, it can become the size of a lemon. It surrounds the urethra, the passage which carries urine from the bladder through the penis during urination. The prostate gland secretes fluid, which forms part of the semen in which sperm are transported. During sexual activity and orgasm, the semen enters the urethra and passes along it through the penis to the outside (ejaculation).
A prostate biopsy is ordered only when the physician has used prior diagnostic tools that indicate an
abnormal prostate. Prostate biopsies are usually performed by a urogenital system specialist (urologist). Special precautions will be required before the biopsy if the patient has a history of abnormal bleeding or is currently taking a blood-thinning medication.
Prostate cancer starts in the cells of the prostate gland. Prostate cancer usually grows slowly and can often be cured or managed successfully. The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as needed to keep the body healthy and functioning properly. Sometimes, however, the process goes wrong—cells become abnormal and form more cells in an uncontrolled way. These extra cells form a mass of tissue, called a growth or tumor. Tumors can be benign, which means not cancerous, or malignant, which means cancerous. Prostate cancer occurs when a malignant tumor forms in the tissue of the prostate gland.
A person is suspected of having cancer after a digital rectal exam and blood tests (including a prostate-specific antigen, or PSA, test) indicate the presence of an abnormal lump or mass on the prostate. The definitive test for prostate cancer is a prostate biopsy. In the biopsy, the doctor (usually a urologist) will remove a small piece of prostate tissue with a hollow needle. This sample is then checked under the microscope for the presence of cancerous cells. If the biopsy reveals no cancerous cells, either the patient does not have prostate cancer, or the prostate biopsy missed the tumor. If the doctor believes the biopsy missed a tumor based on other factors such as the patient's family history, a particular irregularity in the digital rectal exam, or a rising PSA density, a follow-up biopsy is usually done in six months. Seventy-five percent of men have negative primary prostate biopsies.
There are three types of prostate biopsies: transrectal, transurethral, and transperineal. The transrectal prostate biopsy is guided by a transrectal ultrasound (TRUS) through the anus and into the rectum. The transurethral biopsy is performed with a lighted cytoscope up through the urethra so the doctor can look directly at the prostate gland. The transperineal biopsy collects the tissue through a small incision in the perineum (the region of the abdomen surrounding the anal opening). The transrectal and transperineal prostate biopsies both use spring-loaded needles to collect their samples as quickly, efficiently, and painlessly as possible. The biopsy probe can collect between six and 13 samples, depending on how many the doctor decides is necessary for an accurate diagnosis.
In the transrectal biopsy, transrectal ultrasound guides the doctor and the biopsy probe to the proper place. Patients who opt for this prostate biopsy may experience a small amount of bleeding from the rectum as well as blood and urine in the semen afterwards. In transrectal ultrasound a small probe is placed in the rectum and high-frequency sound waves are released from the probe. These sound waves bounce off the prostate tissue and an image is created on a monitor. Since normal prostate tissue and prostate tumors reflect the sound waves differently, the test can be used to detect tumors. Though the insertion of the probe into the rectum may be slightly uncomfortable, the procedure is generally painless and takes about 20 minutes.
The transurethral biopsy inserts a cystoscope (a narrow tubular device) into the urethra, the tube in men that carries urine from the bladder out of the body and carries semen during ejaculation. It is accessed through the opening of the penis. Local anesthesia is given to numb the area. The doctor looks directly at the prostate through the cytoscope and then inserts a cutting loop to extract tissue. The cutting loop works by turning and extracting a small amount of tissue with each turn.
QUESTIONS TO ASK YOUR DOCTOR
- Which type of prostate biopsy do you recommend for me and why?
- What if I decide not to have a biopsy?
- When can I expect results of the biopsy?
- What care will I need immediately following the biopsy?
The doctor inserts a needle into the perineum, the region of the abdomen that surrounds the anal opening, to access the prostate. Patients opting to undergo the transperineal biopsy may be put under general anesthesia if they wish to be unconscious during the biopsy. Men who opt to have the trans-perineal biopsy performed may experience some tenderness as well as blood in the semen for one to two months afterwards.
As of early 2008, prostate cancer was the most commonly diagnosed malignancy among adult males in Western countries. Although prostate cancer is often very slow growing, it can be aggressive, especially in younger men. Given its slow growing nature, many men with the disease die of other causes rather than from the cancer itself. In 2007, there were more than 218,000 new cases of prostate cancer and more than 27,000 deaths from the disease in the United States. More than 2 million men in the United States who have been diagnosed with prostate cancer at some point were still alive as of 2007, according to the American Cancer Society (ACS). The Canadian Cancer Society reported about 22,000 new cases of prostate cancer and 4,300 deaths in 2007. It is the number one cancer among Canadian men accounting for 27% of all cancers in males.
Before undergoing the biopsy, a patient may take antibiotics to reduce the risk of infection after the prostate biopsy. The patient also should stop taking anti-inflammatory drugs, such as aspirin or ibuprofen, that may increase the risk of bleeding after the biopsy. Finally, the doctor may also order an enema before the prostate biopsy to remove feces and gas that may complicate a transrectal biopsy.
Biopsy —The surgical removal and microscopic examination of living tissue for diagnostic purposes.
Cell differentiation —The shape and arrangement of cells.
Digital rectal examination —A routine screening test that is used to detect any lumps in the prostate gland or any hardening or other abnormality of the prostate tissue. The doctor inserts a gloved and lubricated finger (digit) into the patient's rectum, which lies just behind the prostate. Typically, since a majority of tumors develop in the posterior region of the prostate, they can be detected through the rectum.
Pathologist —A doctor who specializes in the diagnosis of disease by studying cells and tissues under a microscope.
Prostate-specific antigen —A protein made by the cells of the prostate that is increased by both BPH and prostate cancer.
Urethra —The tube that carries urine from the bladder out of the body and in the male also carries semen during ejaculation.
Urologist —A doctor who specializes in diseases of the urinary tract and reproductive system.
Only minimal pain is associated with the three prostate biopsy procedures, since doctors commonly use a local anesthesia to numb the tested area. After having the prostate biopsy, men may experience blood in their urine and their semen for a few weeks or up to two months afterwards. Some soreness or minimal bleeding (after the transperineal biopsy) may also be experienced for a few days. Some doctors recommend having someone drive the patient home after the biopsy to avoid unpleasantness or soreness. Also, patients who opt for local or general anesthesia may be groggy for a short time after the prostate biopsy and need to be driven home by another person. Patients may return to normal activities as soon as they feel able. The patient should drink plenty of fluids to help reduce any burning sensation and the chances of a urinary tract infection .
A prostate biopsy performed with a needle is a low-risk procedure. The possible complications include some bleeding into the urethra, bleeding from the rectum, an infection, a temporarily lowered sperm count, or an inability to urinate. These complications are treatable and the doctor should be notified of them. Cytoscopy is generally a very safe procedure. The most common complication is an inability to urinate due to a swelling of the urethra. A catheter (tube) may have to be inserted to help drain out the urine. If there is an infection after the procedure, antibiotics are given to treat it. In very rare instances, the urethra or the bladder may be perforated because of the insertion of the instrument. If this complication occurs, surgery may be needed to repair the damage.
The biopsy results are considered normal if the prostate tissue samples show no sign of inflammation, and if no cancerous cells are detected. However, if a microscopic analysis of the prostate tissue reveals a malignancy (cancer), a pathologist will assign the tumor a numerical score in order to estimate how aggressive the tumor is, based on the most common pattern of cell differentiation. The most commonly used grading system is called the Gleason grading system. The Gleason system produces the Gleason score, which is helpful in classifying the stage and grade of prostate cancer. From the tissue extracted in the biopsy, a pathologist judges the cells. If the cancerous cells look very similar to the healthy cells, the cancerous cells are called well-differentiated. If the cancerous cells are very different from the healthy cells, however, they are called poorly differentiated. The pathologist studies the patterns of cancerous cells underneath a microscope and will assign the tumor a number from 1 to 5. Then based on the second most common pattern of cell differentiation, the pathologist assigns a second number of 1 through 5. The sum of these two numbers is the patient's Gleason score. The Gleason score can range from 2 through 10. Most of the prostate cancer cases diagnosed have Gleason grades of 5, 6, or 7. The more aggressive forms of prostate cancer have scores of 8, 9, or 10. Prostate cancer cases with a Gleason score below 4 are very rare, as they usually do not warrant the biopsy in the first place.
The first member of the care team is usually the patient's primary care physician, who is commonly a family practice doctor, general practitioner, or internal medicine doctor. Once the primary physician suspects a problem, he or she may perform the digital rectal exam and bloods test in the physician's office. Sometimes the primary physician refers the patient to a specialist called a urologist. It is usually the urologist who performs the biopsy. The biopsy can be performed in a physician's office, a hospital operating room, or a surgery center. Once tissue samples are taken during the biopsy, they are examined by a pathologist, a doctor who specializes in diagnosing diseases by studying cells and tissue under a microscope. During the biopsy, there is usually a nurse present. An anesthesiologist may also be present if the patient receives anesthesia. Once a diagnosis of prostate cancer is confirmed, the patient is sent to a cancer specialist called an oncologist.
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Ken R. Wells