The prostate is a muscular, walnut-sized gland that surrounds
part of the urethra, the tube that transports urine and sperm out of the body.
(A gland is a group of cells that secretes chemicals that act on or control the
activity of other cells or organs.)
The main function of the prostate is to produce semen, the milky
fluid that transports sperm. Sperm is produced in the testicles, which also
produce the main male hormone testosterone. Testosterone stimulates the growth
and function of the prostate during puberty, as well as the production of
prostatic fluid for semen.
During sexual climax (orgasm), the muscles of the prostate
contract to push the semen through the urethra and out through the penis. The
urethra also carries urine, a waste product made by the kidneys and stored in
the bladder. When the penis is erect during sexual intercourse, the flow of
urine is blocked from the urethra, allowing only semen to be ejaculated at
orgasm.
Where is the prostate located?
The prostate is located directly beneath the bladder and in
front of the rectum. Because the upper portion of the urethra passes through the
prostate, if the gland becomes enlarged it can obstruct the passage of urine or
semen through the urethra.
What is prostate cancer?
Prostate cancer is the most common cancer in men, and the second
leading cause of cancer death among men in the U.S. More than 180,000 men in the
U.S. will be diagnosed with prostate cancer this year, and more than 40,000 will
die of the disease. Eighty percent of men who reach age 80 have prostate cancer.
Prostate cancer is a malignant tumor that usually begins in the
outer part of the prostate. In most men, the cancer grows very slowly. In fact,
many men with the disease will never know they had the condition. Early prostate
cancer is confined to the prostate gland itself, and the majority of patients
with this type of cancer can live for years with no problems.
Prostate cancer is characterized by both "grade" and "stage."
The size and extent of the tumor determine its stage. Early stage prostate
cancer, Stages T1 and T2, are limited to the prostate gland. Stage T3 prostate
cancer has advanced to tissue immediately outside the gland. Stage T4 prostate
cancer has spread to other parts of the body.
What causes prostate cancer?
Like many cancers, the cause of prostate cancer is unknown. But
doctors do know that it is more common in African-American men and men with a
family history of the disease. The male sex hormone testosterone also
contributes to its growth.
What are the symptoms of prostate cancer?
Prostate cancer, by nature, is silent in its initial stages. Its
symptoms don’t appear until later, when patients may notice a need to urinate
frequently, particularly at night. Prostate cancer may also cause a difficulty
or inability to urinate, a weak or interrupted flow of urine or painful and
burning urination. Other symptoms may include painful ejaculation, blood in
urine or semen, and frequent pain or stiffness in the lower back, hips or
extremities.
Who is at risk for prostate cancer?
The number of cases of prostate cancer has declined among white
American men. The incidence of the disease in black men and the mortality rate
among black men is more than twice that of white men, according to the American
Cancer Society.
The following are some of the risk factors for prostate cancer:
Age. The greatest risk factor for prostate cancer is
age. More than 75 percent of all prostate cancers are diagnosed in men older
than 65 years.
Family history. Men whose relatives have had prostate
cancer are considered to be at high risk. Having a father or brother with the
disease doubles your risk for prostate cancer, according to the American Cancer
Society. Therefore, screening for prostate cancer should be started at age 40 in
men with a family history of the disease.
To date, two genes have been identified that predispose a man to
prostate cancer. Experts estimate that the hereditary form of prostate cancer
accounts for just 9 percent of all cases.
Race. African Americans have the highest incidence of
prostate cancer. They are 30 to 50 percent more likely to develop prostate
cancer than other races in the U.S. Japanese and African men living in their
native countries have a low incidence of prostate cancer. Rates for these groups
increase sharply when they immigrate to the U.S. African Americans, therefore,
represent another group of men for whom prostate cancer screening should begin
at age 40. The increase in the incidence of prostate cancer in African American
men suggests an environmental connection, possibly related to high-fat diets,
inadequate exposure to the sun, exposure to heavy metals such as cadmium,
infectious agents, or smoking.
Diet. Research also suggests high dietary fat may be a
contributing factor. The disease is much more common in countries in which meat
and dairy products are dietary staples, compared with countries in which the
basic diet consists of rice, soybean products, and vegetables.
Male hormones. High levels of male hormones called
androgens may increase the risk of prostate cancer for some men, according to
the American Cancer Society. Research is currently under way to determine
whether medicines that lower androgen levels can lower the risk of prostate
cancer.
Sedentary lifestyle. You may be able to reduce your
risk for prostate cancer by getting regular exercise and maintaining your
optimal weight.
How is prostate cancer detected?
The most effective means of detecting prostate cancer early is
through a screening, which involves a digital rectal exam and measuring the
amount of prostate-specific antigen (PSA) in the blood.
The PSA test is believed to detect most prostate cancers. PSA is
a protein secreted by the prostate into the bloodstream. Elevated levels of this
antigen may indicate the presence of prostate cancer.
If cancer is suspected, a prostate biopsy (removal of tiny
pieces of prostate tissue) will be performed. By removing a tissue sample from
the tumor and examining it, doctors can confirm or rule out a diagnosis of
cancer and determine whether the disease has spread to other organs.
What if prostate cancer is diagnosed?
Fortunately, most prostate cancers have not spread at the time
they are diagnosed, and the cancer is most often confined to the prostate gland.
To help predict the aggressiveness of the prostate cancer, your
physician will look at your PSA levels before the biopsy and will also calculate
the "Gleason Score." The Gleason Score is a sum of the grades of the two most
common prostate tumors. After looking at microscopic sections of the biopsied
prostate tissue, the pathologist assigns a grade (from 1 to 5, with 1 being
closest to normal appearance and 5 being least normal) to the tumors based on
their appearance. The Gleason Score is therefore a score that ranges from 2 to
10, with 2 representing the least aggressive form (confined to the gland) and 10
representing the most aggressive form of cancer (highest risk of spreading
outside the gland).
From the PSA levels and the Gleason Score, a treatment plan is
devised. For men with a low risk of the cancer having spread outside the gland,
staging studies such as bone scans and computed tomography scans are not needed.
Men with cancer with a higher likelihood of spreading may require these staging
studies to determine where the cancer may have spread.
What are the treatment options for prostate cancer?
Physicians tailor prostate cancer treatment plans to their
patient’s needs, taking into account the type of cancer, the age of the
individual, the degree to which the cancer has spread and the general health of
the patient.
- Observation. For men with low-risk cancer, observation may be an initial strategy.
- Laparoscopic radical prostatectomy. A minimally invasive procedure,
laparoscopic prostatectomy removes the prostate gland. Laparoscopic prostatectomy is offered at only a handful of medical centers in the country. Unlike conventional surgery, a laparoscopic
prostatectomy requires only five button-hole incisions. Through these
incisions, a surgeon uses a laparoscope—a tiny camera—and surgical
instruments to conduct the operation and remove the prostate.
- Robotic radical prostatectomy. Robotic prostate cancer surgery is
offered at some institutions. During the procedure, surgeons use robotic
arms to guide the laparoscope through small incisions to remove the
cancerous prostate and affected tissue. Various robotic systems are
available, which may consist of a 3-armed robot connected to a remote
console. The surgeon operates the system while seated at the console. Foot
pedals are used for control, and 3-dimensional displays provide a unique
depiction of the surgical field.
- Open radical prostatectomy. Open radical prostatectomy removes the
entire prostate with an incision in the lower abdomen. Since the prostate
wraps around the urethra, once it is removed the surgeon must reconnect the
bladder with the urethra.
-
Radiation therapy. Radiation therapy uses high energy x-rays to
kill cancer cells and shrink tumors. Radiation can be produced from a
machine outside the body (external radiation) or by putting materials that
produce radiation (radioisotopes) through thin plastic tubes into the area
in which the cancer cells are found (internal radiation).
- Interstitial brachytherapy (seed implantation). Interstitial
brachytherapy is a form of radiation therapy. A radiation oncologist and
urologist implant radioactive pellets or "seeds" into the prostate, and the
pellets radiate the prostate and surrounding tissue over time.
- Intensity-modulated radiotherapy. An advanced form of radiotherapy
called intensity-modulated radiotherapy has shortened the duration of
prostate cancer treatment by several weeks. With computer guidance, high
doses of radiotherapy can be delivered precisely to the tumor, reducing the
risk to normal tissue.
-
Cryotherapy. Small needle-shaped probes can be inserted into the
prostate to freeze the gland to temperatures lethal to a prostate cancer.
This minimally invasive, incision-free procedure is performed either on an
outpatient basis or with a one-night hospital admission. Patients recover in
a matter of days and usually experience minimal after effects.
- Hormone therapy. Hormone therapy is a prostate cancer treatment
that alters the body’s hormone balance to prevent certain cancers from
growing. Hormone therapy may be accomplished using drugs that alter the way
hormones work or with surgery that removes hormone-producing organs such as
the testes.
- Chemotherapy. Chemotherapy involves the use of drugs to kill cancer
cells. Chemotherapy may be taken orally or injected into a vein.
Chemotherapy is usually a systemic treatment, which means that the drugs
enter the bloodstream, travel through the body and can kill cancer cells
anywhere in the body, including the prostate.
What is the outlook for prostate cancer?
Eighty-nine percent of the men diagnosed with prostate cancer
will survive at least 5 years, while 63% will survive 10 years or longer.
Because prostate cancer is a slowly growing disease, many
affected men will die from other causes. Evidence also indicates that many
patients detect their prostate cancer at a curable stage because of annual
screening.
© Copyright 1995-2008 The Cleveland Clinic Foundation. All rights reserved
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on 9/1/2008...#8634
