Prostate cancer

What is Prostate cancer?

Prostate cancer is a tumor found in the male reproductive system. Malignancy of this gland is the most commonly diagnosed cancer in American males and is the second leading cause of cancer deaths among men. Prostate cancer is rare before age 50, but thereafter its incidence increases substantially with each decade of life. Besides increasing age, risk factors include a family history of prostate cancer, certain occupational exposures (such as to cadmium and to tire or rubber manufacturing), and probably a high-fat diet.

The cancer is usually slow growing, commonly discovered during routine screening. It is often an incidental finding at autopsy after death from other causes.

How is it diagnosed?

History: Symptoms appear late in the course of this disease and may be those of urinary obstruction or infection including frequent urination, a weak or interrupted urine stream, having to strain to urinate, and pain or burning during urination. Bone pain is a common symptom of advanced prostate cancer representing spread (metastasis) to bones, especially the spine, pelvic bones, and ribs. If pelvic nerves are invaded, pain in the low back, pelvis, or thighs may result. Prostate cancer can spread to the brain, lungs, liver and other organs, producing varying symptoms.

Physical exam: Screening is ordinarily done by feeling the prostate, by inserting a finger into the rectum (digital rectal examination). If a rock-hard nodule is felt, the suspicion of cancer is raised, and the nodule should be biopsied. However, digital examination cannot detect small or early prostatic tumors.

Tests: Prostate-specific antigen (PSA), a protein produced only by the prostate, is a much more sensitive indicator of prostate cancer. By measuring PSA in the blood, even microscopic tumors can be detected. But, PSA is not very specific. It is elevated also in other non-cancerous diseases of the prostate including benign prostatic hypertrophy, a very common disorder, and prostatitis. In general, the higher the PSA level, the more likely that cancer will be found on biopsy.

Transrectal ultrasound (TRUS) is another diagnostic means. TRUS demonstrates the size and location of lesions within the prostate, and can also detect extension of tumor through the capsule. An ultrasound probe is inserted into the rectum, and is used to evaluate the size of the prostate and locate any tumors. Although sensitive, TRUS is not specifically diagnostic for prostate cancer, and is expensive. Therefore, it is seldom used for routine screening. It is used to further evaluate an abnormal digital exam and/or PSA.

In individuals suspected of having prostate cancer, a needle biopsy of the suspicious nodule is done to obtain a definite diagnosis. TRUS may be used during the procedure to guide placement of the biopsy needle, decreasing the likelihood of missing a small tumor.

Microscopic examination of the biopsy specimen not only provides the diagnosis, but also determines the grade of the cancer. Grade refers to the microscopic characteristics and growth pattern of the tumor cells, and is an index of tumor aggressiveness. If the tumor resembles normal prostate tissue microscopically, it is said to be a low-grade cancer and will probably not grow aggressively. A high-grade cancer is more likely to progress more rapidly, invade, or spread to other areas of the body.

Once prostate cancer has been confirmed by biopsy, it is necessary to determine its stage. Stage refers to the extent to which the tumor has spread, and this will influence its treatment. The stage might not be known with certainty until surgery is performed, but other tests can provide useful information.

Elevated serum levels of prostatic acid phosphatase (PAP, a prostatic enzyme) suggest either local extension or metastasis. However, PAP can be misleading, since manipulation of the prostate during digital rectal examination or other procedures can cause transient elevation. Elevated serum alkaline phosphatase and/or serum calcium suggests bone metastasis. Bone scan is the best procedure for detecting bone metastases; plain x-rays can also detect bone metastases, but are most useful when the bone scan is uncertain.

MRI is used to evaluate the prostate, pelvic contents, and lymph node involvement. CT scans are less accurate than MRI for staging prostate cancer, and are not routinely used.

Diagnostic tests are used to monitor progress after treatment. PSA levels should decrease after treatment going to zero when surgery or radiation are potentially curative. Subsequently, a rising PSA signals recurrent tumor growth.

Lymphangiography (a special x-ray of the lymphatic vessels) may be performed in individuals with advanced or high-grade disease with a high likelihood of lymph node involvement.

How is Prostate cancer treated?

The major approaches are no treatment, surgery, radiation, or hormonal therapy. Choice of treatment depends upon the grade and stage of the disease, the individual's age, general health, and the individual's preference. Staging, along with grading, is essential for determining appropriate treatment. Prostate cancer that is localized (i. e. , confined to the prostate) does not always require treatment, particularly if the tumor is small and low-grade, and the individual's life expectancy is less than ten years. If the life expectancy is longer, whether or not to treat this cancer is highly controversial. But in most such cases either surgery or radiation therapy should be considered.

Radical prostatectomy involves removal of the prostate, seminal vesicles, and part of the vas deferens, and is standard treatment for early stage tumors. This operation is often curative for cancer that has not spread beyond the prostate. Individuals with more advanced tumors are usually not candidates for this type of surgery; however, in some cases surgical removal of the tumor may be useful to relieve urinary obstruction or other symptoms.

Radiation therapy is an alternative to radical prostatectomy. Radiation can be delivered by external beam radiotherapy, or internally by surgical implantation of radioactive pellets into the prostate called "seeding. " Recurrence of cancer is somewhat higher with external radiation therapy than after radical prostatectomy.

For more advanced tumors, radiation therapy is the established treatment but is not considered curative. Such tumors usually get smaller after radiation but in most cases eventually recur. Radiation is also used to help relieve the pain of bone metastases.

Hormonal therapy consists of androgen deprivation, since most prostate cancer growth is stimulated by androgens, the male sex hormones). This type of treatment is indicated for individuals with cancer that has spread beyond the prostate, and will only relieve symptoms and slow down the progress of the disease (palliative). Androgen deprivation may be accomplished by surgical removal of the testes (orchiectomy). It is more often done through drug therapy, including drugs that inhibit androgen secretion, drugs that block androgen receptors, and female hormones (usually not employed because of side effects like breast enlargement and increased risk of heart failure.

Cryosurgery (freezing the cancer by insertion of a probe cooled with liquid nitrogen) can be used to treat localized prostate cancer. However, there is not yet enough information about outcomes to compare it with established treatments.

Chemotherapy has a role in the treatment of advanced disease, after hormonal therapy has failed. However, its effectiveness is limited.

Pelvic lymphadenectomy (removal of pelvic lymph nodes) may be performed, either by open abdominal surgery or by laparoscopy. The lymph nodes are then examined microscopically for tumor.

Medications

Information	Brand	Generic	Label	Rating
	Propecia	Finasteride

Premarin (Conjugated Estrogens), Eulexin (Flutamide), Casodex (Bicalutamide)

What might complicate it?

In early prostate cancer, complications are related to diagnostic procedures and treatment. Needle biopsy is a minimally invasive procedure, but does carry a slight risk of bleeding and infection. Radical prostatectomy frequently results in impotence and/or urinary incontinence, which may be either temporary or permanent. Radiation therapy can also result in gradual loss of sexual function. Radiation therapy has its own complications. Diarrhea can occur due to rectal inflammation (proctitis), and may be short-term or chronic. Chronic loss of sexual function is another complication. In advanced prostate cancer, complications may occur due to the disease itself. Enlargement of the primary tumor may obstruct the urinary tract, which may lead to urinary tract infection. Encroachment of tumor on regional nerves may produce neurological impairment as well as pain. Lymphatic obstruction may result in lower extremity swelling (lymphedema). Bone metastases can lead to pathological fractures (e. g. , compression fractures of the spine).

Other metastatic complications can occur, depending on the site of metastasis. The treatment of advanced prostate cancer itself can also produce complications. Adverse effects of hormonal therapy include impotence, breast enlargement, nausea, hot flashes, adrenal insufficiency, liver toxicity, and thromboembolism. Orchiectomy may result in permanent impotence and sterility. Adverse effects of chemotherapy include nausea and vomiting, hair loss, and depressed immunity due to bone marrow toxicity.

Predicted outcome

Prognosis depends primarily on the stage, size, and grade of the tumor. Earlier stage and smaller tumor size have the better prognosis. Cancer that is localized to the prostate can often be eradicated completely. More advanced cancers usually cannot; most of these tumors eventually recur locally. In addition, undetected lymph node and distant metastases are more likely with more advanced tumors than with earlier stage, small tumors.

The lower the grade of the tumor, the better the prognosis. Low-grade tumors usually progress very slowly. High-grade tumors tend to behave more aggressively, growing rapidly and spreading (metastasizing) early. Metastatic disease to lymph nodes and/or distant sites has a poor prognosis. Hormonal treatment usually relieves symptoms, but relapse commonly occurs within several years. After relapse, survival is limited. Choice of treatment, if choices are available, has some influence on prognosis. For localized cancer, ten-year recurrence rates are somewhat lower after radical prostatectomy than after conventional external beam radiation. Prognosis may also be influenced by other factors. For example, there is evidence that prognosis is worse in individuals who smoke, who have a high fat diet, or who are black.

Alternatives

Prostate cancer must be differentiated from other causes of prostatic enlargement and/or elevated PSA. These include benign prostatic hypertrophy, chronic prostatitis, and prostatic abscess.

Appropriate specialists

Urologist, medical oncologist, and radiation oncologist.

Last updated 28 May 2012