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HPV na Prática Clínica

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HPV na Prática Clínica

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What is prostate cancer?

The prostate is a gland in the male reproductive system that helps produce semen, the thick fluid that carries sperm cells. The walnut-sized gland is located beneath a man's bladder and surrounds the upper part of the urethra, the tube that carries urine from the bladder. Prostate function is regulated by testosterone, a male sex hormone produced mainly in the testicles.Prostate cancer is a major health concern for American men. Although the disease is rare before age 50, experts speculate that most elderly men have at least traces of it. More than 200,000 new cases and about 30,000 deaths are attributed to prostate cancer each year in the U.S. For reasons not fully understood, African-American men have the highest frequency of prostate cancer in the world and the highest death rate from the disease. In other parts of the world -- notably Asia, Africa, and Latin America -- prostate cancer is rare. Prostate cancer is typically a very slow growing tumor, often causing no symptoms until advanced stages. Most men with prostate cancer die of other causes -- many without ever realizing that they have the disease. But once prostate cancer begins to grow more rapidly or spreads outside the prostate, it is dangerous. Although the disease tends to progress slowly, it is generally fatal if it spreads beyond the prostate gland itself. Prostate cancer in its early stages (confined to the prostate gland or spread to surrounding tissue, including the rectum and bladder) can be cured. Fortunately, about 85% of American men with prostate cancer are diagnosed in the early stages.Cancer that has spread beyond the prostate to distant tissues (such as the bones, liver, and lungs) is not curable, but it often can be controlled for years. About a third of men whose prostate cancer becomes widespread can expect to live five years or more.

What causes it?

Prostate cancer affects mainly older men. Four out of five cases are diagnosed in men over 65, but less than 1% in men under 50. Men with a family history of prostate cancer are three times more likely to die of it than is the general population. On a case-by-case basis, doctors cannot say with certainty what causes prostate cancer, but experts generally agree that diet contributes to the risk. Men who consume large amounts of fat -- particularly from red meat and other sources of animal fat -- are most likely to develop advanced prostate cancer. The disease is much more common in countries where meat and dairy products are dietary staples than in countries where the basic diet consists of rice, soybean products, and vegetables. The underlying factor linking diet and prostate cancer is probably hormonal. Fats stimulate production of testosterone and other hormones, and testosterone acts to speed the growth of prostate cancer. High testosterone levels may spur dormant prostate cancer cells into activity. Some findings suggest that high testosterone levels also influence the initial onset of prostate cancer. Eating meat may be risky for other reasons: Meat cooked at high temperatures produces cancer-causing substances that directly affect the prostate. A few other risk factors have been noted. Welders, battery manufacturers, rubber workers, and workers frequently exposed to the metal cadmium seem to be abnormally vulnerable to prostate cancer. Researchers know more about what will not cause prostate cancer than what will. No proven link exists between prostate cancer and an active sex life, vasectomy, masturbation, use of alcohol or tobacco, circumcision, infertility, infection of the prostate, or a common noncancerous condition called benign prostatic hyperplasia (BPH) that causes an enlarged prostate gland. Most elderly men experience an enlarged prostate to some degree.

What are the symptoms?

Early prostate cancer rarely causes symptoms. Once a malignant tumor causes the prostate gland to swell significantly, or once cancer spreads beyond the prostate, the following symptoms may be present:

• A frequent need to urinate, especially at night.
• Difficulty starting or stopping the urinary stream.
• A weak or interrupted urinary stream.
• A painful or burning sensation during urination or ejaculation.
• Blood in urine or semen.

Symptoms of advanced prostate cancer include:

• Dull, incessant pain or stiffness in the pelvis, lower back, or upper thighs; arthritic pain in the bones of those areas.
• Loss of weight and appetite, fatigue, nausea, or vomiting.

Call Your Doctor If:

• You have difficulty urinating or find that urination is painful or otherwise abnormal. Your doctor will examine your prostate gland to determine whether it is enlarged, inflamed with an infection, or may have cancer.
• You have chronic pain in your lower back, pelvis, upper thighbones, or other bones. Ongoing pain without explanation always merits medical attention. Pain in these areas can have various causes but may be from the spread of advanced prostate cancer.

How do I know if I have prostate cancer?

The best way to detect prostate cancer in its early stages is unknown. Because most malignant prostate tumors originate in the part of the gland nearest the rectum, many cancers can be detected during routine rectal examinations. Many doctors recommend an annual rectal exam, supplemented by a prostate-specific antigen (PSA) blood test, starting at age 50 for most men. The screenings are recommended beginning at age 40 for African Americans and those with a family history of prostate cancer. On the other hand, some doctors don't recommend PSA at all because the test isn't proven to save lives and may lead to unnecessary tests, such as prostate biopsy. PSA is a protein whose level tends to increase in the presence of prostate cancer, making it more effective than rectal exam in detecting early prostate cancer. Together, the two screening measures offer the best chance of detecting prostate cancer while it is localized and most treatable. Prostate cancer may also be discovered incidentally during treatment for urinary problems. Because of the possibility of a false-positive PSA reading, it is important to discuss this test with your doctor before having one. If routine screening arouses suspicion and PSA levels are elevated, a doctor will look at the prostate using an ultrasound instrument inserted in your rectum. X-rays of the urinary tract, along with blood and urine studies, are performed routinely to aid diagnosis. Performing a biopsy will confirm cancer diagnosis: Guided by ultrasound images, the doctor inserts a needle into the prostate and extracts a small tissue sample from the suspicious area. A pathologist then studies the sample under a microscope to determine whether cancer cells are present. In order to determine if the cancer has spread outside the prostate gland, doctors usually arrange CT scans, bone scans, chest X-rays, or other imaging tests.

What are the treatments?

Since prostate cancer is often slow growing and may not be fatal in many men, some men -- after discussing the options with their doctors -- opt for "watchful waiting." Watchful waiting involves monitoring the prostate cancer for signs that it is becoming more aggressive but otherwise not treating it. This approach is recommended more commonly for men who are older or suffer from other life-threatening conditions. In these cases, the cancer may be growing so slowly that it's not likely to be fatal.Once the decision is made to treat a cancer, other factors, such as a patient's age and general health, affect the type of treatment given. Decisions about how to treat this cancer are complex, and many men seek a second opinion -- sometimes from a specialist at a major cancer center -- before making a treatment decision. Depending on when the disease is diagnosed, treatment includes some combination of radiation therapy, surgery, hormone therapy, and rarely chemotherapy. Localized prostate cancer usually can be cured with surgery, radiation therapy, or cryosurgery -- freezing malignant cells with liquid nitrogen. The choice is made on a case-by-case basis and depends on many factors. The standard operation -- a radical prostatectomy -- involves the removal of the prostate and nearby lymph nodes. In many cases, surgeons can remove the gland without cutting nerves that control penile erection or bladder function, making such complications as impotence or incontinence less common than in the past. Depending on the man's age and the amount of surgery needed to remove all the cancer, nerve-sparing techniques allow about 40%-65% of men who were able to get erections before surgery to be able to do so after surgery.After surgery, most men experience some degree of incontinence but usually regain complete urinary control. Impotence can be treated in a variety of ways -- including with medications such as Levitra or Viagra. Incontinence can be managed with special disposable underwear, condom catheters, or penile clamps; in three cases out of four that don't resolve on their own, incontinence can be eliminated altogether with surgically inserted sphincter implants in the urethra. Radiation therapy may be given as an alternative or follow-up to surgery for cancer that has not spread. If cancer has spread to nearby tissue, radiation is the preferred treatment; it is also used in advanced cases to relieve pain from the spread of cancer to bones. Incontinence and impotence also occur with radiation, and some studies have shown similar results to surgery.Permanent radioactive seed implants allow for delivery of a high dose of radiation to the prostate with limited damage to surrounding tissues. During the procedure, radioactive seeds (iodine-125) are implanted into the prostate gland using ultrasound guidance. The implants remain in place permanently and become inactive after about 10 months. Even advanced cases that cannot be cured may be controlled for years with hormone therapy, sometimes supplemented by other treatments. Hormone therapy slows the cancer's growth by cutting off the testosterone supply, although the treatment's effectiveness may decrease over time. Testosterone can be removed from the bloodstream by surgically removing the testicles or by administering female hormones such as estrogen or other drugs that block testosterone production. Men generally prefer the testosterone-blocking drug treatment because it is effective, less invasive, and causes fewer side effects than surgery or female hormone drugs. If the testicles are removed, the scrotum can be left intact with testicular implants put in place. The goal of prostate cancer treatment is a cure, and is likely in men diagnosed with early prostate cancer. All prostate cancer survivors should be examined regularly and have their PSA levels monitored closely. As with other types of cancer, new treatments are being developed for advanced prostate cancer. Researchers are using radiation and hormone therapy in innovative ways and are testing the effectiveness of chemotherapy on patients who do not respond to other treatments.

How can I prevent prostate cancer?

Evidence regarding fat in the diet and prostate cancer is conflicting. But high dietary fat has been linked with increased prostate cancer. To lower your dietary fat, eat more fish, poultry, fresh vegetables, fruits, and low-fat dairy products. In general, eat less red meat; remove skin from poultry before cooking; and cut down on butter, margarine, and oils. There is some evidence that heating meat to high temperatures creates cancer-causing substances. To avoid these substances, try poaching or roasting, not frying or barbecuing.

Reviewed by Michael W. Smith, MD, September 2003.