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What You Need To Know About Prostate Cancer

What is the prostate gland?

The prostate gland is an organ that is located at the base or outlet (neck) of the urinary bladder. (See the diagram.) 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. Another 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. 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. During normal aging, however, the gland usually grows larger. This enlargement with aging is called benign prostatic hypertrophy (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.

What is prostate cancer?

Prostate cancer is a malignant (cancerous) tumor (growth) that consists of cells from the prostate gland. 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). 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.

Why is prostate cancer important?

In 1999, 185,000 new cases of prostate cancer were diagnosed in the United States. What's more, 31,000 deaths related to prostate cancer are expected in the year 2000. Thus, prostate cancer is the most common malignancy in American men and the second leading cause of deaths from cancer, after lung cancer. Most experts in this field, therefore, recommend that beginning at age 40, all men should undergo yearly screening for prostate cancer.

What causes prostate cancer?

The cause of prostate cancer is unknown, but the cancer is thought not to be related to benign prostatic hypertrophy (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, between 50 and 80 percent of them may have prostate cancer!

Genetics (heredity), as just mentioned, plays a role in the risk of developing a prostate cancer. For example, black American men have a higher risk of getting prostate cancer than do Japanese or white American men. Environment, diet, and other unknown factors, however, can modify such genetic predispositions. For example, prostate cancer is uncommon in Japanese men living in their native Japan. However, when these men move to the United States, their incidence of prostate cancer rises significantly. Prostate cancer is also more common among family members of individuals with prostate cancer. Thus, a person whose father, grandfather, or even uncle has prostate cancer is at an increased risk for also developing prostate cancer. To date, however, no specific prostate cancer gene has been identified and verified. (Genes, which are situated on chromosomes within the nucleus of cells, are the chemical compounds that determine specific traits in individuals.)

Testosterone, the male hormone, 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.

Environmental factors, such as cigarette smoking and diets that are high in saturated fat, seem to increase the risk of prostate cancer. 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.

What are the symptoms of prostate cancer?

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 (the PSA, discussed below) or as a hard nodule (lump) in the prostate gland. Usually, the doctor first feels the nodule during a routine digital (done with the finger) rectal examination. (Note in the diagram that the prostate gland is right in front of the rectum.) As the cancer enlarges and presses on the urethra, 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.

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. The doctor on 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.

What are the screening tests for prostate cancer?

Screening tests are those that are done at regular intervals to detect a disease such as prostate cancer at an early stage. If the result of a screening test is normal, the disease is presumed not to be present. If a screening test is abnormal, the disease is then suspected to be present, and further tests usually are needed to confirm the suspicion (that is, to make the diagnosis definitively). Prostate cancer usually is suspected initially because of an abnormality of one or both of the two screening tests that are used to detect prostate cancer. These screening tests are a digital rectal examination and a blood test called the prostate specific antigen (PSA).

In the digital rectal examination, the doctor feels (palpates) the prostate gland with his index finger in the rectum to detect abnormalities of the gland. Thus, a lump, irregularity, or hardness felt on the surface of the gland is a finding that is suspicious for prostate cancer. Accordingly, doctors usually recommend doing a digital rectal examination annually in men age 40 and over.

The PSA test is a simple, reproducible, and accurate blood test. It is used to detect a protein (the prostate specific antigen) that is released from the prostate gland into the blood. Most importantly, the level of the PSA is usually higher in people with prostate cancer than in people without the cancer. The PSA, therefore, is valuable as a screening test for prostate cancer. Accordingly, doctors usually recommend doing a PSA annually in men age 50 and over. Furthermore, for men who have high risks for prostate cancer as discussed above, most doctors recommend starting the PSA screening at an even younger age (for example, at age 40).

Results of the PSA test under 4 nanograms per milliliter of blood are generally considered normal. (See the next two sections on false-positive elevations of the PSA and on refinements in the PSA test.) Results between 4 and 10 are considered borderline. These borderline values are interpreted in the context of the patient's age, symptoms, signs, family history, and changes in the PSA levels over time. Results higher than 10 are considered abnormal, suggesting the possibility of prostate cancer. The higher the PSA value, the more likely the diagnosis of prostate cancer. Moreover, the level of PSA tends to increase when the cancer has progressed from organ-confined prostate cancer to local spread to distant (metastatic) spread. Very high values, such as 30 or 40 and over, are usually caused by prostate cancer.

What are false-positive elevations in the PSA test?

False-positive elevations in the PSA are increases in the PSA that are caused by conditions other than prostate cancer. For example, benign prostatic hypertrophy (BPH) and infection or inflammation of the prostate (prostatitis) from whatever cause can elevate the PSA. Note also that a rectal examination or an ejaculation within the prior 48 hours can sometimes elevate the PSA. False-positive elevations are usually in the 4 to10 range, but they can go as high as 25 or 30. At these higher levels, however, caution in the interpretation of the test is warranted because a prostate cancer may well be present. Non-prostatic diseases or infections, medications, foods, smoking, and alcohol do not cause false-positive elevations of the PSA.

The ability of the PSA test to detect prostate cancer (called the sensitivity of the test) is high. The reason for this is that most patients, although not all, with prostate cancer have a borderline or an abnormally elevated PSA. The ability of the test to exclude other diagnoses (called the specificity of the test), however, is lower because of the other conditions that can cause false-positive elevations of the PSA.

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What are the treatment options for prostate cancer?

Deciding on treatment can be daunting, partly because the options for treatment today are far better than they were ten years ago, but also because not enough reliable data are available on which to base the decisions. Accordingly, scientifically controlled, long term studies are still needed to compare the benefits and risks of the various treatments.

To decide on treatment for an individual patient, doctors categorize prostate cancers as organ-confined (localized to the gland), locally advanced (a large prostate tumor or one that has spread only locally), or metastatic (spread distantly or widely). The treatment options for organ-confined prostate cancer or locally advanced prostate cancer usually include surgery, radiation therapy, hormonal therapy, cryotherapy, combinations of some of these treatments, and watchful waiting. A cure for metastatic prostate cancer is, unfortunately, unattainable at the present time. The treatments for metastatic prostate cancer, which include hormonal therapy and chemotherapy, therefore, are considered palliative. By definition, the aims of palliative treatments are, at best, to slow the growth of the tumor and relieve the symptoms of the patient.

Other factors considered in choosing treatment include the age, general health, and preference of the individual and the Gleason score and stage of the cancer. The results of the PSA test sometimes also can help to decide on the treatment. For example, a borderline elevation of the PSA (4-10), if shown to be due to a prostate cancer, suggests that the cancer is confined to the gland. If other tests also point to an organ-confined tumor, surgery or possibly radiation can be considered to attempt a cure. In contrast, a very high PSA (for example, over 30 or 40) raises the possibility of metastases. If the metastases are then confirmed by other tests, the treatment options would be limited to hormonal therapy or chemotherapy.

PSA tests also should be done periodically after treatment to help assess the results of treatment. For example, an increasing PSA suggests growth or spread of the cancer, despite the treatment. In contrast, a decreasing PSA indicates improvement. As a matter of fact, a post-treatment PSA of zero may indicate complete control or cure of the cancer.

What about surgical treatment for prostate cancer?

The surgical treatment for prostate cancer is commonly referred to as a radical or total prostatectomy, which is the removal of the entire prostate gland. Since 1990, the radical prostatectomy has been the most common treatment for prostate cancer in the United States. This operation is done in about 36% of patients with organ-confined (localized) prostate cancer. The American Cancer Society estimates a 90% cure rate nationwide when the disease is confined to the prostate and the entire gland is removed. The potential complications of a radical prostatectomy include the risks of anesthesia, local bleeding, impotence (loss of sexual function) in 30%-70% of patients, and incontinence (loss of control of urination) in 3%-10% of patients.

Great strides have been made in lowering the frequency of the complications of radical prostatectomy. These advances have been accomplished largely through improved anesthesia and surgical techniques. The improved surgical techniques, in turn, stem from a better understanding of the key anatomy and physiology of sexual potency and urinary continence. Specifically, the recent introduction of nerve-sparing techniques for the prostatectomy has helped to reduce the frequency of impotence and incontinence.

If post-treatment impotence does occur, it can be treated by sildenafil (Viagra) tablets, injections of such medications as alprostadil (Caverject) into the penis, various devices to pump up or stiffen the penis, or a penile prosthesis (an artificial penis). Incontinence after treatment often improves with time, special exercises, and medications to improve the control of urination. Occasionally, however, incontinence requires implanting an artificial sphincter around the urethra. The artificial sphincter is made up of muscle or other material and is designed to control the flow of urine through the urethra.

What about radiation therapy for prostate cancer?

The goal of radiation therapy is to damage the cancer cells and stop their growth or kill them. This works because the rapidly dividing (reproducing) cancer cells are more vulnerable to destruction by the radiation than are the neighboring normal cells. Clinical trials have been conducted using radiation therapy for patients with organ-confined (localized) prostate cancer. These trials have shown that radiation therapy resulted in a rate of survival (being alive) at 10 years after treatment that is comparable to that for radical prostatectomy. Incontinence and impotence can occur as complications of radiation therapy, as with surgery, although perhaps less often than with surgery. More data are needed, however, on the risks and benefits of radiation therapy beyond 10 years, especially because late recurrences (reappearances) of the cancer can sometimes occur after radiation.

Choosing between radiation and surgery to treat organ-confined prostate cancer involves considerations of the patient's preference, age, and co-existing medical conditions (fitness for surgery), as well as of the extent of the cancer. Approximately 30% of patients with organ-confined prostate cancer are treated with radiation. Sometimes, oncologists combine radiation therapy with surgery or hormonal therapy in efforts to improve the long-term results of treatment in the early or later stages of prostate cancer.

Radiation therapy can be given either as external beam radiation over perhaps 6 or 7 weeks or as an implant of radioactive seeds (brachytherapy) directly into the prostate. In external beam radiation, high energy x-rays are aimed at the tumor and the area immediately surrounding it. In brachytherapy, radioactive seeds are inserted through needles into the prostate gland under the guidance of transrectally taken ultrasound pictures. Brachy, from the Greek language, means short. The term brachytherapy thus refers to placing the treatment (radiation therapy) directly into or a short distance away from the cancerous target tissue. The theoretical advantage of brachytherapy over external beam radiation is that delivering the radiation energy directly into the prostate tissue should minimize damage to the surrounding tissues and organs. The actual advantages or disadvantages of brachytherapy as compared to external beam radiation, however, are still being studied.

What is watchful waiting?

Watchful waiting is observing a patient while no treatment is given. Such a patient usually has an organ-confined tumor and no symptoms. Understand, however, that although watchful waiting involves no actual treatment, the patient still needs close follow-up and monitoring. The follow-up involves frequent visits to the doctor, perhaps every three to six months. The visits include questions about new or worsening symptoms and digital rectal examinations for any change in the prostate gland. In addition, blood tests are done to watch for a rising PSA and imaging studies can be conducted to detect the spread of the cancer. If the history, examinations, or any of the tests signal the possibility of an advancing cancer, the watchful waiting usually is discontinued and treatment is recommended.

This option of watchful waiting actually has been chosen over a therapeutic intervention, such as surgery or radiation, in up to 30% of patients who have organ-confined (localized) prostate cancer. The main reason for taking a course of watchful waiting is that prostate cancers generally grow more slowly than most other cancers. Thus, many localized prostate cancers found at an early stage can take years or sometimes even decades to spread locally and metastasize. Therefore, watchful waiting seems to make sense for organ-confined (localized) prostate cancers in men who are elderly. It is also a reasonable decision in men who have tiny (seen only with a microscope) tumors and a low PSA (for example, in the 4-10 range or lower). Additionally, watchful waiting often is the most appropriate choice in men who are ill with other serious medical diseases, such as heart or lung disease, poorly controlled high blood pressure, diabetes, AIDS, or other cancers.

Watchful waiting in prostate cancer, however, remains controversial. Some medical authors have stated outright that it is not a good choice. They point out that few doctors would just watch other cancers to see whether they would spread without treatment. Furthermore, the treatment for an individual could become less effective in the future if and when the cancer does progress. Finally, one expert summarized some recently published information on watchful waiting. He indicated that among men with organ-confined (localized) prostate cancer, the development of distant spread (metastasis) and death from the cancer was 50 percent higher in those who received no treatment than in those who underwent surgical removal of the prostate (radical prostatectomy).

Can prostate cancer be prevented?

No specific measures are known to prevent the development of prostate cancer. 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. Screening is done, as mentioned previously, by routine yearly digital rectal examinations beginning at age 40 and the addition of an annual PSA test beginning at age 50. 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 to prevent the progression of prostate cancer. For example, 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, and vitamin E might slow the growth of prostate tumors in ways that are not yet understood.