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University Hospital > Cancer Services > About Prostate Cancer > Introduction

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Prostate Cancer Description

Like other cancers, prostate cancer is a disease of cells growing out of control. Spurred by changes in the genes, the glandular cells of the prostate multiply abnormally. These cancer cells may cross tissue barriers and may then spread throughout the body.

Background

Most cancers are named after the part of the body where the cancer first starts. Prostate cancer starts in the prostate gland.

The prostate gland is found only in men; therefore, only men get prostate cancer. It is just below the bladder and in front of the rectum. The urethra, the tube that carries urine, runs through the prostate. The prostate normally starts out about the size of a walnut. By the time a man is age 40, the prostate may already have grown to the size of an apricot; by age 60, it may be as big as a lemon.

The prostate gland makes a fluid that is part of semen, the fluid that contains sperm. Nerves found next to the prostate take part in causing an erection of the penis, and treatments that remove or damage these nerves can cause impotence, or problems with erections.

How it spreads

Compared with most cancers, prostate cancer tends to grow slowly. It may be decades from the time the earliest cell changes can be detected under a microscope until the cancer gets big enough to cause symptoms.

When cancer grows through the prostate capsule, it invades nearby tissues. It also may spread to the lymph nodes of the pelvis, or it may spread throughout the body (metastasize) via the bloodstream or the lymphatic system.

Causes 

Although we don't yet know exactly what causes prostate cancer, there may be a genetic link. Genes are the basic units of heredity. Having certain genes can result in a higher risk of getting prostate cancer. However, heredity appears to be linked to only about 10 percent of prostate cancers.

Types of Prostate Cancertop of page

The prostate usually is healthy in younger men. As a man grows older, however, the prostate gland frequently becomes a source of trouble. The three most common prostate problems are inflammation (prostatitis), prostate enlargement (benign prostatic hyperplasia/BPH), and prostate cancer. Neither prostatitis nor prostate enlargement is known to cause cancer. However, it is possible for men who have one or both of these conditions to develop prostate cancer as well.

Prostatitis

Prostatitis, or prostate inflammation, can cause difficult or painful urination that often is accompanied by a burning sensation, a strong and frequent urge to urinate that often results in only small amounts of urine, and pain in the lower back or abdomen.

The causes of prostititis are unclear. Sometimes, it is the result of a bacterial infection. Occasionally, prostatitis is accompanied by chills and a high fever. When prostatitis is the result of a bacterial infection, it usually can be cleared up with antibiotics.

Benign Prostatic Hyperplasia (BPH) 

Benign prostatic hyperplasia (BPH) is an enlarged prostate. Benign means noncancerous and hyperplasia means excessive growth of tissue. BPH is the result of small noncancerous growths inside the prostate. It is not known what causes these growths, but it may be related to hormone changes that occur with aging. By age 60, more than half of all American men have microscopic signs of BPH, and by age 70, more than 40 percent will have prostate enlargement that can be felt on a physical examination.

As the prostate enlarges, it presses against the bladder and the urethra, blocking the flow of urine. Therefore, a man with BPH may find it difficult to initiate a urine stream or to maintain more than a dribble. He also may need to urinate frequently, or he may have a sudden, powerful urge to urinate. Many men are forced to get up several times a night; others have an annoying feeling that the bladder is never completely empty. BPH usually does not affect sexual function.

Statisticstop of page

Prostate cancer is the second most common type of cancer found in American men, just behind skin cancer. According to the American Cancer Society, (ACS) there will be about 179,300 new cases of prostate cancer in the United States this year, and about 37,000 men will die of this disease.

Although men of any age can get prostate cancer, it is found most often in men over 50. By age 50, one-third of American men have microscopic signs of prostate cancer, and by age 75, half to three-quarters of men?s prostates will have cancerous changes. Most of these cancers either remain latent, producing no signs or symptoms, or indolent, never posing a serious threat to health.

A much smaller number of men will actually be treated for prostate cancer. About 16 percent of American men will be diagnosed with prostate cancer during their lifetime; 8 percent will develop significant symptoms; and 3 percent will die of the disease.

The late 1980s saw a sharp rise in the number of cases being diagnosed. By 1997, the number of new cases of prostate cancer reached an estimated 209,000, more than double the 90,000 cases identified just 10 years earlier. However, recent statistics show that the incidence rate (the number of cases diagnosed per 100,000 men per year) has begun to decline.

Much of the dramatic surge in the detection of prostate cancer cases can be traced to the growing use of procedures and tests that, intentionally or not, reveal small, symptom-free cancers, many of which otherwise would have gone unnoticed.

Before the 1980s, prostate cancer usually was diagnosed wither when it caused symptoms or during a digital rectal exam (DRE).

It was in the mid-1980s, when doctors began using the transurethral resection of the prostate (TURP) procedure to treat benign prostate enlargement, that small, even microscopic cancers began turning up in prostate tissue samples removed at surgery.

The number of prostate cancer diagnoses rose even faster in the late 1980s when doctors began to add the blood test for prostate-specific antigen (PSA) to regular checkups. A National Cancer Institute (NCI) study showed that doctors increased their use of the PSA test for men ages 65 or older--the age group most susceptible to prostate cancer--from 1,430 per 100,000 men in 1988 to 18,000 per 100,000 men in 1991.

Until recently, death rates, too, were edging steadily upward. In 1982, prostate cancer killed 17 out of every 100,000 American men. By 1991, this number increased to 25 of every 100,000. The figures for African-American men are even higher--55 of every 100,000. However, in the past several years, death rates, like incidence rates, appear to have been declining.

No one knows why prostate death rates went up. It is possible that, as more older men were diagnosed with prostate cancer, the disease was sometimes listed as the cause of death even when a man died of something else.

The reasons for the more recent death-rate decrease are also unclear, but the decrease may reflect improved treatment, and diagnosis when the cancer is smaller through screening (PSA and digital rectal exams).