The prostate gland is an organ that is located at the base or outlet (neck) of the urinary bladder. The gland surrounds the first part of the urethra. The urethra is the passage through which urine drains from the bladder to exit from the penis. One function of the prostate gland is to help control urination by pressing directly against the part of the urethra that it surrounds. The main function of the prostate gland is to produce some of the substances that are found in normal semen, such as minerals and sugar. Semen is the fluid that transports the sperm to assist with reproduction. A man can manage quite well, however, without his prostate gland. (See the section on surgical treatment for prostate cancer.)
In a young man, the normal prostate gland is the size of a walnut (<30g). During normal aging, however, the gland usually grows larger. This hormone-related enlargement with aging is called benign prostatic hyperplasia (BPH), but this condition is not associated with prostate cancer. Both BPH and prostate cancer, however, can cause similar problems in older men. For example, an enlarged prostate gland can squeeze or impinge on the outlet of the bladder or the urethra, leading to difficulty with urination. The resulting symptoms commonly include slowing of the urinary stream and urinating more frequently, particularly at night. Patients should seek medical advice from their urologist or primary-care physician if these symptoms are present.
As the cancer advances, however, it can spread beyond the prostate into the surrounding tissues (local spread). Moreover, the cancer also can metastasize (spread even farther) throughout other areas of the body, such as the bones, lungs, and liver. Symptoms and signs, therefore, are more often associated with advanced prostate cancer.
In a young man, the normal prostate gland is the size of a walnut (<30g). During normal aging, however, the gland usually grows larger. This hormone-related enlargement with aging is called benign prostatic hyperplasia (BPH), but this condition is not associated with prostate cancer. Both BPH and prostate cancer, however, can cause similar problems in older men. For example, an enlarged prostate gland can squeeze or impinge on the outlet of the bladder or the urethra, leading to difficulty with urination. The resulting symptoms commonly include slowing of the urinary stream and urinating more frequently, particularly at night. Patients should seek medical advice from their urologist or primary-care physician if these symptoms are present.
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| Prostate Cancer |
Prostate Cancer
Prostate cancer is a malignant (cancerous) tumor (growth) that consists of cells from the prostate gland. Generally, the tumor usually grows slowly and remains confined to the gland for many years. During this time, the tumor produces little or no symptoms or outward signs (abnormalities on physical examination). However, all prostate cancers do not behave similarly. Some aggressive types of prostate cancer grow and spread more rapidly than others and can cause a significant shortening of life expectancy in men affected by them. A measure of prostate cancer aggressiveness is the Gleason score (discussed in more detail later in this article), which is calculated by a trained pathologist observing prostate biopsy specimens under the microscope.Causes Of Prostate Cancer
The cause of prostate cancer is unknown, but the cancer is not thought to be related to benign prostatic hyperplasia (BPH). The risk (predisposing) factors for prostate cancer include:
- Advancing age,
- Genetics (heredity),
- Hormonal influences,
- And such environmental factors as toxins, chemicals, and industrial products.
The chances of developing prostate cancer increase with age. Thus, prostate cancer under age 40 is extremely rare, while it is common in men older than 80 years of age. As a matter of fact, some studies have suggested that among men over 80 years of age, 50%-80% of them may have prostate cancer! More than 80% of prostate cancers are diagnosed in men older than 65 years of age.
As mentioned previously, African-American men are 1.6 times more likely than white men to develop prostate cancer. They are also 2.4 times more likely to die from their disease as compared to white men of a similar age. These differences in diagnosis and death rates are, however, more likely to reflect a difference in factors such as environmental exposure, diet, lifestyle, and health-seeking behavior rather than any racial susceptibility to prostate cancer.
Recent studies indicate that this disparity is progressively decreasing with chances of complete cure in men undergoing treatment for organ-confined prostate cancer (cancer that is limited to within the prostate without spread outside the confines of the prostate gland), irrespective of race.
Genetics (heredity), as just mentioned, plays a role in the risk of developing a prostate cancer.
Prostate cancer is more common among family members of individuals with prostate cancer. This risk may be two to three times greater than the risk for men without a family history of the disease. Earlier age at diagnosis (<60 years) in a first-degree relative (father or brother) and disease affecting more than one relative also increases the risk for developing prostate cancer.
Testosterone, the male hormone produced by the testicles, directly stimulates the growth of both normal prostate tissue and prostate cancer cells. Not surprisingly, therefore, this hormone is thought to be involved in the development and growth of prostate cancer. The important implication of the role of this hormone is that decreasing the level of testosterone should be (and usually is) effective in inhibiting the growth of prostate cancer.
Recent evidence has suggested that sexually transmitted infections are risk factors for developing prostate cancer. Men with a history of sexually transmitted infections have a 1.4 times greater chance of developing prostate cancer as compared men without this history.
Although still unproven, environmental factors, such as cigarette smoking and diets that are high in saturated fat, seem to increase the risk of prostate cancer. There is also a suggestion that obesity leads to an increased risk of having more aggressive, larger prostate cancer, which results in a poorer outcome after treatment. Additional substances or toxins in the environment or from industrial sources might also promote the development of prostate cancer, but these have not yet been clearly identified. Geographical influences also seem to play a role in the development of prostate cancer with men living in the Scandinavian and North American countries being at a higher risk for the disease as compared to those residing in Asian countries.
Of note, there is no proven relationship between the frequency of sexual activity and the chances of developing prostate cancer.
Prostate Cancer Symptoms and Signs
In the early stages, prostate cancer often causes no symptoms for many years. As a matter of fact, these cancers frequently are first detected by an abnormality on a blood test or as a hard nodule (lump) in the prostate gland.
Occasionally, the doctor may first feel a hard nodule during a routine digital (done with the finger) rectal examination. The prostate gland is located immediately in front of the rectum.
Rarely, in more advanced cases,
- The cancer may enlarge and press on the urethra. As a result, the flow of urine diminishes and urination becomes more difficult.
Patients may also experience burning with urination or blood in the urine. As the tumor continues to grow, it can completely block the flow of urine, resulting in a painfully obstructed and enlarged urinary bladder. These symptoms by themselves, however, do not confirm the presence of prostate cancer. Most of these symptoms can occur in men with non-cancerous (benign) enlargement of the prostate (the most common form of prostate enlargement). However, the occurrence of these symptoms should prompt an evaluation by the doctor to rule out cancer and provide appropriate treatment.
Furthermore, in the later stages, prostate cancer can spread locally into the surrounding tissue or the nearby lymph nodes, called the pelvic nodes.
The cancer then can spread even farther (metastasize) to other areas of the body.
Symptoms of metastatic disease include:
- fatigue,
- malaise,
- and weight loss.
The doctor during a rectal examination can sometimes detect local spread into the surrounding tissues.
That is, the physician can feel a hard, fixed (not moveable) tumor extending from and beyond the gland. Prostate cancer usually metastasizes first to the lower spine or the pelvic bones (the bones connecting the lower spine to the hips), thereby causing back or pelvic pain. The cancer can then spread to the liver and lungs.
Metastases (areas to which the cancer has spread) to the liver can cause pain in the abdomen and jaundice (yellow color of the skin) in rare instances. Metastases to the lungs can cause chest pain and coughing.
Prostate Cancer Diagnosis
Prostate cancer is diagnosed from the results of a biopsy of the prostate gland. If the digital rectal exam of the prostate or the PSA blood test is abnormal, a prostate cancer is suspected. A biopsy of the prostate is usually then recommended. The biopsy is done from the rectum (trans-rectally) and is guided by ultrasound images of the area. A small piece of prostate tissue is withdrawn through a cutting needle.
The TRUS-guided Tru-Cut biopsy is currently the standard method to diagnose prostate cancer. Although initially a 6-core set was the standard, currently most experts advocate sampling a minimum of 10-12 pieces of the prostate to improve the chances of detection of the cancer and also to provide a better idea regarding the extent and areas of involvement within the prostate. Multiple pieces are taken by sampling the base, apex, and mid gland on each side of the gland. More cores may be sampled to increase the yield, especially in larger glands.
A pathologist, a specialist physician who analyzes tissue samples under a microscope, then examines the pieces under the microscope to assess the type of cancer present in the prostate and the extent of involvement of the prostate with the tumor.
One also can get an idea about the areas of the prostate that are involved by the tumor by assessing which of the pieces contain the cancer and which of them do not. Another very important assessment that the pathologist makes form the specimen is the grade (Gleason's score) of the tumor. This indicates how different the cancer cells are from normal prostate tissue. Grade gives an indication of how fast a cancer is likely to grow and has very important implications on the treatment plan and the chances of cure after treatment. A Gleason score of 6 is supposed to indicate low-grade (less aggressive) disease while that of 8-10 demonstrates high grade (more aggressive) cancer; 7 is regarded as somewhere in between these two.
Prostate Cancer Prevention
No specific measures are known for prostate cancer prevention. At present, therefore, we can hope only to prevent progression of the cancer by making early diagnoses and then attempting to cure the disease.
Early diagnoses can be made by
- Screening men for prostate cancer with PSA
- And digital rectal examination.
The purpose of the screening is to detect early, tiny, or even microscopic cancers that are confined to the prostate gland. Early treatment of these malignancies (cancers) can stop the growth, prevent the spread, and possibly cure the cancer.
Based on some research in animals and people, certain dietary measures have been suggested for prostate cancer prevention.
Example for Prostate Cancer Prevention;
- low-fat diets,
- particularly avoiding red meats, have been suggested because they are thought to slow down the growth of prostate tumors in a manner not yet known.
- Soybean products, which work by decreasing the amount of testosterone circulating in the blood, also reportedly can inhibit the growth of prostate tumors.
- Finally, other studies show that tomato products (lycopenes), the mineral selenium, andvitamin E might slow the growth of prostate tumors in ways that are not yet understood.
Recently, studies have shown that certain medications
- Finasteride [Propecia] and Dutasteride [Avodart] decrease the chances of getting prostate cancer when taken over the long term. These medications are currently used for shrinking the size of the prostate and relieving symptoms associated with benign (non-cancerous) enlargement of the prostate. However, they may have a future role for decreasing the chances of development of prostate cancer in men who are at high risk for the disease.