December 06, 2007

Prostate cancer

Prostate cancer is cancer of the small walnut-shaped gland in men that produces seminal fluid, the fluid that nourishes and transports sperm.

For many men a diagnosis of prostate cancer can be frightening, not only because of the threat to their lives, but because of the threat to their sexuality. In fact, the possible consequences of treatment for prostate cancer — which include bladder control problems and erectile dysfunction (ED) or impotence — can be a great concern for some men.

If prostate cancer is detected early — when it's still confined to the prostate gland — you have a better chance of successful treatment with minimal or short-term side effects. Successful treatment of cancer that has spread beyond the prostate gland is more difficult. But treatments exist that can help control prostate cancer.

Signs and symptoms

Prostate cancer often doesn't produce any symptoms in its early stages. That's why many cases of prostate cancer aren't detected until it has spread beyond the prostate.

When signs and symptoms do occur, they may include the following:

Dull pain in your lower pelvic area
Urgency of urination
Difficulty starting urination
Pain during urination
Weak urine flow and dribbling
Intermittent urine flow
A sensation that your bladder doesn't empty
Frequent urination at night
Blood in your urine
Painful ejaculation
General pain in your lower back, hips or upper thighs
Loss of appetite and weight
Persistent bone pain


Cancer is a group of abnormal cells that grow more rapidly than normal cells and that refuse to die. Cancer cells also have the ability to invade and destroy normal tissues, either by growing directly into surrounding structures or after traveling to another part of your body through your bloodstream or lymph system. Microscopic cancer cells develop into small clusters that continue to grow, becoming more densely packed and hard.

The prostate gland is the small, walnut-shaped gland that surrounds the bottom portion ("neck") of a male's bladder and about the first inch of the urinary tube (urethra), the channel that drains urine from the bladder. It's located behind the pubic bone and in front of the rectum. The prostate's primary function is to produce seminal fluid, the fluid that nourishes and transports sperm.

Prostate cancer usually grows slowly and initially remains confined to the prostate gland, where it may not cause serious harm. But if left untreated, prostate cancer can begin to invade tissues and cause damage, and it may spread to others areas of your body where it can cause significant harm. Some forms of prostate cancer are aggressive and can spread quickly to other parts of your body.

What causes prostate cancer and why some types behave differently are unknown. Research suggests that a combination of factors may play a role, including heredity, ethnicity, hormones, diet and the environment.

Risk factors
Knowing the risk factors for prostate cancer can help you determine if and when you want to begin prostate cancer screening. The main risk factors include:

Age. As you get older, your risk of prostate cancer increases. After age 50, your chance of having prostate cancer increases substantially.

Race or ethnicity. For reasons that aren't well understood, African-American men have a higher risk of developing and dying of prostate cancer.

Family history. If a close family member — your father or brother — has prostate cancer, your risk of the disease is greater than that of the average American man.

Diet. A high-fat diet and obesity may increase your risk of prostate cancer. Researchers theorize that fat increases production of the hormone testosterone, which may promote the development of prostate cancer cells.

Surgery to become infertile (vasectomy). Although some studies suggest that men who've had a vasectomy are at increased risk for prostate cancer, no conclusive evidence to support such research has been found. Research on this issue is ongoing.

High levels of testosterone. Because testosterone naturally stimulates the growth of the prostate gland, men who have high levels of testosterone, such as those with hypogonadism or men who use testosterone therapy, are more likely to develop prostate cancer than are men who have lower levels of testosterone. Long-term testosterone treatment could cause prostate gland enlargement (benign prostatic hyperplasia). Also, doctors are concerned that testosterone therapy might fuel the growth of prostate cancer that is already present.

When to seek medical advice

If you have difficulties with urination, see your doctor. This condition doesn't always relate to prostate cancer, but it can be a sign of prostate-related problems.

If you're a man older than 50, you may want to see your doctor to discuss beginning prostate cancer screening. Mayo Clinic doctors, in accordance with the American Cancer Society and the American Urological Association (AUA), recommend having an annual blood test to check for prostate-specific antigen (PSA) beginning at age 50, or earlier if you're at high risk for cancer. If you're black or have a family history of the disease, you may want to begin at a younger age. Mayo Clinic doctors, along with the AUA, also recommend that men have a yearly digital rectal exam beginning at age 40.

Screening and diagnosis

Prostate cancer frequently doesn't produce symptoms. The first indication of a problem may come during a routine screening test. Screening tests include:

Digital rectal exam (DRE). During a DRE, your doctor inserts a gloved, lubricated finger into your rectum to examine your prostate, which is adjacent to the rectum. If your doctor finds any abnormalities in the texture, shape or size of your gland, you may need more tests.

Prostate-specific antigen (PSA) test. A blood sample is drawn from a vein and analyzed for PSA, a substance that's naturally produced by your prostate gland to help liquefy semen. It's normal for a small amount of PSA to enter your bloodstream. However, if a higher than normal level is found, it may be an indication of prostate infection, inflammation, enlargement or cancer.

Transrectal ultrasound. If other tests raise concerns, your doctor may use transrectal ultrasound to further evaluate your prostate. A small probe, about the size and shape of a cigar, is inserted into your rectum. The probe uses sound waves to get a picture of your prostate gland.

Prostate biopsy
If initial test results suggest prostate cancer, your doctor may recommend a prostate biopsy. During a biopsy, small tissue samples are taken and analyzed to determine if cancer cells are present.

To do a biopsy, your doctor inserts an ultrasound probe into your rectum. Guided by images from the probe, your doctor identifies any suspicious areas. Then a fine, hollow needle is aimed at these areas of your prostate. A spring propels the needle into your prostate gland and retrieves a very thin section of tissue.

If an abnormal area is seen on the transrectal ultrasound, your doctor will likely biopsy that area. If no abnormality is seen, eight sections of tissue usually are taken from different areas of your prostate gland. Very large prostate glands may require more than eight biopsies to adequately assess the gland for cancer. A pathologist who specializes in diagnosing cancer and other tissue abnormalities evaluates the samples. From those, the pathologist can tell if the tissue removed is cancerous and estimate how aggressive your cancer is.

Determining how far the cancer has spread
Once a cancer diagnosis has been made, you may need further tests to help determine if or how far the cancer has spread. Many men don't require additional studies and can directly proceed with treatment based on the characteristics of their tumors and the results of their pre-biopsy PSA tests.

Bone scan. A bone scan takes a picture of your skeleton in order to determine whether cancer has spread to the bone. Prostate cancer can spread to any bones in your body, not just those closest to your prostate, such as your pelvis or lower spine.

Ultrasound. Ultrasound not only can help indicate if cancer is present, but also may reveal whether the disease has spread to nearby tissues.

Computerized tomography (CT) scan. A CT scan produces cross-sectional images of your body. CT scans can identify enlarged lymph nodes or abnormalities in other organs, but they can't determine whether these problems are due to cancer. Therefore, CT scans are most useful when combined with other tests.

Magnetic resonance imaging (MRI). This type of imaging produces detailed, cross-sectional images of your body using magnets and radio waves. An MRI can help detect evidence of the possible spread of cancer to lymph nodes and bones.

Lymph node biopsy. If enlarged lymph nodes are found by a CT scan or an MRI, a lymph node biopsy can determine whether cancer has spread to nearby lymph nodes. During the procedure, some of the nodes near your prostate are removed and examined under a microscope to determine if cancerous cells are present.

When a biopsy confirms the presence of cancer, the next step, called grading, is to determine how aggressive the cancer is. The tissue samples are studied, and the cancer cells are compared with healthy prostate cells. The more different the cancer cells are from the healthy cells, the more aggressive the cancer and the more likely it is to spread quickly.

Cancer cells may vary in shape and size. Some cells may be aggressive, while others aren't. The pathologist identifies the two most aggressive types of cancer cells when assigning a grade.

The most common cancer grading scale runs from 1 to 5, with 1 being the least aggressive form of cancer. Known as Gleason scores, these numbers may be helpful in determining which treatment option is best for you. The Gleason score adds the grades of the two most aggressive types of cancer cells; therefore, scoring may range from 2 (non-aggressive cancer) to 10 (very aggressive cancer).

After the level of aggressiveness of your prostate cancer is known, the next step, called staging, determines if or how far the cancer has spread. Your cancer is assigned one of four stages, based on how far it has spread:

Stage I. Signifies very early cancer that's confined to a microscopic area that your doctor can't feel.

Stage II. Your cancer can be felt, but it remains confined to your prostate gland.

Stage III. Your cancer has spread beyond the prostate to the seminal vesicles or other nearby tissues.

Stage IV. Your cancer has spread to lymph nodes, bones, lungs or other organs

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