prostate cancer disease in which cancer develops in the prostate, a gland in the malereproductive system. It occurs when cells of the prostate mutate and begin to multiply out of control. These cells may spread (metastasize) from the prostate to other parts of the body, especially the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, erectile dysfunction and other symptoms.
Rates of prostate cancer vary widely across the world. Although the rates vary widely between countries, it is least common in South and East Asia, more common in Europe, and most common in the United States.
[1] According to the American Cancer Society, prostate cancer is least common among Asian men and most common among black men, with figures for white men in-between.
[2]However, these high rates may be affected by increasing rates of detection.
[4]Prostate cancer develops most frequently in men over fifty. This cancer can occur only in men, as the prostate is exclusively of the male reproductive tract. It is the most common type of cancer in men in the United States, where it is responsible for more male deaths than any other cancer, except lung cancer. However, many men who develop prostate cancer never have symptoms, undergo no therapy, and eventually die of other causes. Many factors, including genetics and diet, have been implicated in the development of prostate cancer.
Prostate cancer is most often discovered by physical examination or by screening blood tests, such as the PSA (prostate specific antigen) test. There is some current concern about the accuracy of the PSA test and its usefulness. Suspected prostate cancer is typically confirmed by removing a piece of the prostate (biopsy) and examining it under a microscope. Further tests, such as X-rays and bone scans, may be performed to determine whether prostate cancer has spread.
Prostate cancer can be treated with surgery, radiation therapy, hormonal therapy, occasionally chemotherapy, proton therapy, or some combination of these. The age and underlying health of the man as well as the extent of spread, appearance under the microscope, and response of the cancer to initial treatment are important in determining the outcome of the disease. Since prostate cancer is a disease of older men, many will die of other causes before a slowly advancing prostate cancer can spread or cause symptoms. This makes treatment selection difficult.[5] The decision whether or not to treat localized prostate cancer (a tumor that is contained within the prostate) with curative intent is a patient trade-off between the expected beneficial and harmful effects in terms of patient survival and quality of life.
treatment
Prostate Cancer Treatment Methods
Treatment for prostate cancer may involve watchful waiting, surgery, radiation therapy, or hormonal therapy. Some patients receive a combination of therapies. In addition, doctors are studying other methods of treatment to find out whether they are effective against this disease. (The “Promise of Cancer Research” section has information about research studies.)
Watchful waiting may be suggested for some men who have prostate cancer that is found at an early stage and appears to be slow growing. Also, watchful waiting may be advised for older men or men with other serious medical problems. For these men, the risks and possible side effects of surgery, radiation therapy, or hormonal therapy may outweigh the possible benefits. Men with early stage prostate cancer are taking part in a study to determine when or whether treatment may be necessary and effective. (See “The Promise of Prostate Cancer Research” section for information about this study.)
Surgery is a common treatment for early stage prostate cancer. The doctor may remove all of the prostate (a type of surgery called radical prostatectomy) or only part of it. In some cases, the doctor can use a new technique known as nerve-sparing surgery. This type of surgery may save the nerves that control erection. However, men with large tumors or tumors that are very close to the nerves may not be able to have this surgery.
The doctor can describe the types of surgery and can discuss and compare their benefits and risks.
- In radical retropubic prostatectomy, the doctor removes the entire prostate and nearby lymph nodes through an incision in the abdomen.
- In radical perineal prostatectomy, the doctor removes the entire prostate through an incision between the scrotum and the anus. Nearby lymph nodes are sometimes removed through a separate incision in the abdomen.
- In transurethral resection of the prostate (TURP), the doctor removes part of the prostate with an instrument that is inserted through the urethra. The cancer is cut from the prostate by electricity passing through a small wire loop on the end of the instrument. This method is used mainly to remove tissue that blocks urine flow.
If the pathologist finds cancer cells in the lymph nodes, it is likely that the disease has spread to other parts of the body. Sometimes, the doctor removes the lymph nodes before doing a prostatectomy. If the prostate cancer has not spread to the lymph nodes, the doctor then removes the prostate. But if cancer has spread to the nodes, the doctor usually does not remove the prostate, but may suggest other treatment.
These are some questions a patient may want to ask the doctor before having surgery:
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Radiation therapy (also called radiotherapy) uses high-energy x-rays to kill cancer cells. Like surgery, radiation therapy is local therapy; it can affect cancer cells only in the treated area. In early stage prostate cancer, radiation can be used instead of surgery, or it may be used after surgery to destroy any cancer cells that may remain in the area. In advanced stages, it may be given to relieve pain or other problems.
Radiation may be directed at the body by a machine (external radiation), or it may come from tiny radioactive seeds placed inside or near the tumor (internal or implant radiation, or brachytherapy). Men who receive radioactive seeds alone usually have small tumors. Some men with prostate cancer receive both kinds of radiation therapy.
For external radiation therapy, patients go to the hospital or clinic, usually 5 days a week for several weeks. Patients may stay in the hospital for a short time for implant radiation.
Hormonal therapy keeps cancer cells from getting the male hormones they need to grow. It is called systemic therapy because it can affect cancer cells throughout the body. Systemic therapy is used to treat cancer that has spread. Sometimes this type of therapy is used to try to prevent the cancer from coming back after surgery or radiation treatment.
There are several forms of hormonal therapy:
- Orchiectomy is surgery to remove the testicles, which are the main source of male hormones.
- Drugs known as luteinizing hormone-releasing hormone (LH-RH) agonists can prevent the testicles from producing testosterone. Examples are leuprolide, goserelin, and buserelin.
- Drugs known as antiandrogens can block the action of androgens. Two examples are flutamide and bicalutamide.
- Drugs that can prevent the adrenal glands from making androgens include ketoconazole and aminoglutethimide.
After orchiectomy or treatment with an LH-RH agonist, the body no longer gets testosterone from the testicles. However, the adrenal glands still produce small amounts of male hormones. Sometimes, the patient is also given an antiandrogen, which blocks the effect of any remaining male hormones. This combination of treatments is known as total androgen blockade. Doctors do not know for sure whether total androgen blockade is more effective than orchiectomy or LH-RH agonist alone.
Prostate cancer that has spread to other parts of the body usually can be controlled with hormonal therapy for a period of time, often several years. Eventually, however, most prostate cancers are able to grow with very little or no male hormones. When this happens, hormonal therapy is no longer effective, and the doctor may suggest other forms of treatment that are under study.
