ABOUT THE PROSTATE

The prostate gland, a key part of the male reproductive system, is linked closely with the urinary system. It is a small gland that secretes much of the liquid portion of semen, the milky fluid that transports sperm through the penis during ejaculation.

The prostate is located just beneath the bladder, where urine is stored, and in front of the rectum. It encircles, like a donut, a section of the urethra. The urethra is the tube that carries urine from the bladder out through the penis. During ejaculation, semen is secreted by the prostate through small pores of the urethra's walls.

The prostate is made up of three lobes encased in an outer covering, or capsule. It is flanked on either side by the seminal vesicles, a pair of pouch-like glands that contribute secretions to the semen. Next to the seminal vesicles run the two vas deferens, tubes that carry sperm from the testicles. The testicles, in addition to manufacturing sperm, produce testosterone, a male sex hormone that controls the prostate's growth and function.

BACK TO TOP

ABOUT PROSTATE CANCER

Prostate cancer is a disease in which malignant (cancer) cells form in the tissues of the prostate. The prostate is a gland in the male reproductive system located just below the bladder and in front of the rectum. It is about the size of a walnut and surrounds the urethra (the tube that empties urine from the bladder). The prostate gland produces fluid that makes up part of the semen.

Prostate cancer is the most common non-skin malignancy in men and is responsible for more deaths than any other cancer, except for lung cancer. However, microscopic cancer is found at autopsy in many if not most men. Approximately 16% of American men will be diagnosed with prostate cancer sometime in their life.

Treatment options and prognosis depend on the stage of the cancer, the Gleason score, and the patient’s age and general health. With greater public awareness, early detection is on the rise and mortality rates are declining. Additionally, new advances in medical technology are enabling cancer patients to go on to live active and productive lives after their treatment.

BACK TO TOP

CAUSES OF PROSTATE CANCER

Prostate cancer is rare in men under 50 years old. However, the risk increases steadily with age. By the time they are 80, more than half of all men will have some cancerous growth, though in most cases it goes unnoticed. Prostate cancer is usually slow-growing and, in men who have it, is often not the cause of death.

The causes of prostate cancer are largely unknown. It is clear that the chances of developing prostate cancer increase in men over 50. Close relatives of men who have had prostate cancer are also more likely to be affected. Ethnic origin appears to play a part: men of African heritage seem to be at highest risk, and men of Far Eastern descent the lowest.

It may be possible to reduce the risk by avoiding a high fat diet through, for example, cutting down on dairy foods and red meat.

Genetic Causes of Prostate Cancer

Prostate cancer seems to run in some families, suggesting an inherited or genetic factor. Having a father or brother with prostate cancer doubles a man's risk of developing this disease. The risk is even higher for men with several affected relatives, particularly if their relatives were young at the time of diagnosis. Scientists have identified several inherited genes that seem to increase prostate cancer risk, but they probably account for only a small fraction of cases. Genetic testing for these genes is not yet available.

Some inherited genes increase risk for more than one type of cancer. For example, inherited mutations of the BRCA1 or BRCA2 genes are the reason that breast and ovarian cancers are much more common in some families. The presence of these gene mutations also increases prostate cancer risk. But they are responsible for a very small percentage of prostate cancer cases.

Possible Environmental Causes of Prostate Cancer

The most consistent risk factors associated with prostate cancer are age, family history and African-American ethnicity. Hormonal factors, as well as high levels of animal fat and red meat in the diet, are also suspected risk factors.

Several occupational studies have linked farming to prostate cancer risk. However, the variety of environmental exposures in the farming community such as pesticides, engine exhausts, solvents, dusts, animal viruses, fertilizers, fuels, and specific microbes, have made it difficult for researchers in previous studies to sort out which of these factors is linked to specific diseases.

Exposure to certain agricultural pesticides may be associated with an increased risk of prostate cancer among pesticide applicators, according to a large recent study known as the AHS (Agricultural Health Study) looking at the causes of cancer and other diseases in the farming community.The AHS is a collaborative effort involving the National Cancer Institute (NCI), the National Institute of Environmental Health Sciences, and the Environmental Protection Agency.

There is also a weak association between prostate cancer and cadmium exposure, associated with the occupational environments of mining and newspaper printing.

Possible Links to Vasectomy

Some studies have raised questions about a possible relationship between vasectomy (an operation to cut or tie off the two tubes that carry sperm out of the testicles) and the risk of developing cancer, particularly prostate and testicular cancer. Such a relationship, if proven, would be of importance, as about one in six men over the age of 35 in the United States has had a vasectomy.

BACK TO TOP

SCREENING & TESTING

This year in the United States, almost 180,000 men will be told that they have prostate cancer. After a diagnosis of prostate cancer, a man and his family face several choices regarding treatment. Decisions involve many factors, personal as well as medical. Before making these decisions, it is very important that he learns about all the options available. With this knowledge, a newly diagnosed prostate cancer patient can participate more confidently with his doctor in planning his individual treatment.

BACK TO TOP

PREVENTION

Prostate cancer can sometimes be associated with known risk factors for the disease. Many risk factors are modifiable though not all can be avoided. Among those factors that appear to aid in prevention are hormone medications, diet adjustment and chemoprevention.

Hormonal Prevention
Studies are underway to discover the role of certain drugs, such as finasteride, that reduce the amount of male hormone as preventive agents for prostate cancer.

Diet and Lifestyle
A diet high in fat, especially animal fat, may be associated with an increased risk of prostate cancer. Increased dietary intake of fruits and vegetables has been associated with a reduced risk of prostate cancer in some studies.

Chemoprevention
Chemoprevention is the use of specific natural or man-made drugs, vitamins, or other agents to reverse, suppress, or prevent cancer growth. Several agents, including difluoromethylornithine (DFMO), isoflavonoids, selenium, vitamins D and E, and lycopene have shown potential benefit in studies. Further studies are needed to confirm this.