Prostate Cancer – Types, Stages and Diagnosis
Prostate cancer is a disease involving growth of malignant/cancerous cells in the prostate. Other names for this type of cancer include prostatic adenocarcinoma, prostatic carcinoma and prostatic sarcoma. The prostate gland in men is situated just below the bladder and in front of the rectum and partly surrounds the urethra, which empties urine from the bladder. It produces some of the fluid that goes to make up the semen and helps provide an alkaline environment for the sperm so that they survive for longer.
A normal human prostate gland weighs an average of about 11 grams. It tends to increase in size as men grow older, sometimes to the extent where the urethra and/or bladder get blocked, causing problems with urination and sexual performance. This condition is known as benign prostatic hyperplasia (BPH) and as the name suggests, it is non-cancerous. Although having benign prostatic hyperplasia does not increase the risk of prostate cancer, it is possible for the symptoms of BPH to be confused with those of prostate cancer because of their similarity.
If the prostate cancer becomes more advanced, it can spread to nearby tissue and then to other parts of the body, by penetrating the lymph system or blood vessels and travelling to form secondary (metastatic) tumors.
Fast Facts about Prostate Cancer
- Adenocarcinoma belong amongst the most common forms of prostate cancer
- It is rare for men under 40 to get prostate cancer and the risk of developing it thereafter increases with age
- Prostate cancer goes through four main stages numbered I – IV
- A scoring system known as the Gleason score is used to assess how aggressive the cancer is
- There are a number of diagnostic tests used to detect and monitor prostate cancer
- Reducing intake of alcohol and animal fats, eating fresh fruit and vegetables and taking regular exercise can reduce the risk of developing prostate cancer
- Treatment options include simple monitoring (“wait and see”), radiotherapy, hormone therapy and surgery
Types of Prostate Cancer
By far the most common type of prostate cancer is adenocarcinoma, which is usually slow-growing and stays in the prostate until the late stages. However, a rare subtype of adenocarcinoma is mucinous adenocarcinoma, which is aggressive and tends to form metastases in the bone. Other types of prostate cancer include small cell carcinoma, which is aggressive and forms in nerve cells to begin with and squamous cell carcinoma. Both these types do not increase levels of PSA and are, therefore, difficult to detect in their early stages. Prostate sarcomas can also occur in childhood but these are extremely rare.
Causes of Prostate Cancer
The exact underlying mechanisms of prostate cancer are not fully understood. It is an age-related disease, with genetics and lifestyle also playing a role.
Risk Factors for Prostate Cancer
Although prostate cancer is rarely found in men under the age of forty, the risk increases with age after that. As a matter of fact, it is the third most common cause of cancer fatalities in men. There is a genetic component (you are more likely to develop prostate cancer if you have a father or brother with the disease) and African-American men are also at greater risk, as are men who work with certain chemicals, alcoholics and those who eat a diet which is high in animal fats.
Symptoms of Prostate Cancer
The symptoms of prostate cancer include trouble urinating (i.e. delayed start of urination, pain or burning while urinating, straining, poor flow, dribbling or leakage after urination and not being able to empty the bladder fully). Blood may also be present in the urine and also in the semen. Ejaculation is sometimes painful and there may also be pain in the hips and back.
Diagnosing Prostate Cancer
In suspected cases of prostate cancer, there are several tests that can be used to diagnose the disease. The first of these is the digital rectal exam (DRE), which, as the name suggests, involves a manual examination where a medical practitioner puts on gloves, lubricates their finger and inserts it up the rectum to feel the prostate through the rectal wall. The presence of lumps or other abnormalities, while not necessarily conclusive, indicates that further diagnostic steps may be necessary. There are several such steps that can be taken. One is the prostate-specific antigen (PSA) test, which measures PSA levels in the blood. PSA is made by the prostate and secreted into the blood. The blood of a man with prostate cancer will contain higher levels of PSA than that of a man with a healthy prostate. However, higher PSA levels also occur in cases of benign prostatic hyperplasia or prostate infection/inflammation, so again, the PSA test is not conclusive.
Another diagnostic test for prostate cancer is called transrectal ultrasound. A probe, which emits high-energy sound waves, is inserted into the rectum. The resulting echoes that occur when the sound waves bounce off internal organs produce a computer-generated picture (sonogram) of the prostate and surrounding area.
A biopsy of the prostate is another test that can be carried out to diagnose prostate cancer. This involves taking samples of cells/tissues from the prostate and examining them under a microscope. This method will confirm the diagnosis once and for all. There are two types of biopsy that can be performed to diagnose prostate cancer: transrectal biopsy, which involves inserting a thin needle into the prostate via the rectum (transrectal ultrasound is used to make sure the needle goes in the right place) and transperineal biopsy, where the needle is inserted into the prostate via the skin between the rectum and scrotum.
If prostate cancer cells are found in a biopsy sample, the pathologist will assign a rating known as the Gleason score to indicate how aggressive the prostate cancer may be. The Gleason score ranges from 2 to 10. A score of 2 – 4 indicates low-level cancer, a score of 5 – 7 corresponds to intermediate-level cancer (most prostate cancers come into this range) and a score of 8 – 10 indicates a highly aggressive cancer. To reach the final Gleason score, an initial grading system is used. The pathologist examines the biopsied sample to find the area where the cancer is worst and assigns a grade of 1 – 5 to that area, with 5 being the worst possible grade. Then he/she looks at the second worst area and assigns another grade of 1 – 5. Adding the two grades together gives the Gleason score.
There are four stages of prostate cancer:
- The least advanced is Stage I, where the cancer is found only in one half (or less) of one lobe in the prostate. Levels of PSA are lower than 10 and the prostate feels normal during a rectal examination.
- Stage II. Although the cancer is still confined to the prostate, it is more advanced than stage I. PSA levels are higher and so is the Gleason score. Stage II may be divided into stage IIA and IIB, with IIB being more advanced than IIA.
- Stage III. The cancer has moved beyond the outer layer of the prostate and has possibly spread to the seminal vesicles. If this has occurred, a case of prostate cancer is designated as stage III whatever the Gleason score and PSA levels are.
- Stage IV. The cancer has spread beyond the seminal vesicles to the lymph nodes, bones, and/or other organs such as the rectum, pelvic wall or bladder. Again, prostate cancer will be classed as stage IV if these events have occurred, regardless of the Gleason score and PSA levels.
Various diagnostic procedures are used as part of the staging process:
- A radionuclide bone scan, which is carried out by injecting a tiny amount of radioactive material into a vein. A scanner is then used to generate computer- or film-based images of its eventual distribution in the bones. The radioactive substance tends to accumulate in bone cells that are undergoing a lot of activity. Since cancer cells divide more rapidly than normal cells, cancerous areas of the bone will therefore appear as “hot spots”.
- Magnetic resonance imaging (MRI), also known as nuclear magnetic resonance imaging (NMRI). This takes detailed, computerized pictures of any tumors within your body. It works by using a magnet to align the magnetization of the body’s hydrogen atoms, followed by a short burst of radio waves to knock the alignment out. When the radio waves are stopped, the hydrogen atoms realign themselves, and the rate at which they do so depends on their location in the body. The signals they send is what creates the picture that is sent to the computer.
- A computerized tomography (CT) or computerized axial tomography (CAT) scan. This is an X-ray based technique that takes pictures within the body at various angles and produces a computer-generated image.
- Pelvic lymphadenectomy. This involves surgical removal of lymph nodes in the pelvis, followed by examination under a microscope to determine the presence of cancer cells.
- Seminal vesicle biopsy. The seminal vesicles are glands that, like the prostate, are responsible for producing seminal fluid. A biopsy is used to remove some of this fluid and examine it under the microscope to see if there are any cancer cells.
Treatment Options for Prostate Cancer
The treatment will depend on the stage of the disease and the age of the patient. A doctor may simply recommend monitoring the condition without treatment for someone in the very early stages of the disease or for an older man with other medical problems. Regular biopsies and monitoring of PSA levels are then carried out and active treatment is started if the symptoms worsen.
Treatments include surgery, radiotherapy and/or hormonal therapy.
Prevention of Prostate Cancer
The preventative role of diet is well-documented – traditional Japanese and southern Mediterranean diets, both of which are low in red meat and high in fresh vegetables, are known to be associated with a lower risk of prostate cancer. If you cut down on alcohol and animal fats, take regular exercise, get daily sunshine, drink green tea and eat plenty of fresh fruit and vegetables, then you will be cutting the risk of developing prostate cancer.
Coping with Prostate Cancer
If prostate cancer is diagnosed, the prognosis depends on several factors. These include the patient’s age and general health and whether the prostate cancer is newly-diagnosed or recurring. However, the main factors that influence prognosis are the Gleason score, the level of PSA and also the stage it has reached. Knowing the stage that the cancer has reached will enable the doctor to propose the best possible treatment.