When you're told you have prostate cancer, it's natural to wonder what may have caused the disease. But no one knows the exact causes of prostate cancer. Doctors seldom know why one man develops prostate cancer and another doesn't.

However, research has shown that men with certain risk factors are more likely than others to develop prostate cancer. A risk factor is something that may increase the chance of getting a disease.

Studies have found the following risk factors for prostate cancer:

• Age over 65: Age is the main risk factor for prostate cancer. The chance of getting prostate cancer increases as you get older. In the United States, most men with prostate cancer are over 65. This disease is rare in men under 45.
  
  
• Family history: Your risk is higher if your father, brother, or son had prostate cancer.
  
  
• Race: Prostate cancer is more common among black men than white or Hispanic/Latino men. It's less common among Asian/Pacific Islander and American Indian/Alaska Native men.
  
  
• Certain prostate changes: Men with cells called high-grade prostatic intraepithelial neoplasia (PIN) may be at increased risk of prostate cancer. These prostate cells look abnormal under a microscope.
  
  
• Certain genome changes: Researchers have found specific regions on certain chromosomes that are linked to the risk of prostate cancer. According to recent studies, if a man has a genetic change in one or more of these regions, the risk of prostate cancer may be increased. The risk increases with the number of genetic changes that are found. Also, other studies have shown an elevated risk of prostate cancer among men with changes in certain genes, such as BRCA1 and BRCA2.

Having a risk factor doesn't mean that a man will develop prostate cancer. Most men who have risk factors never develop the disease.

Many other possible risk factors are under study. For example, researchers have studied whether vasectomy (surgery to cut or tie off the tubes that carry sperm out of the testicles) may pose a risk, but most studies have found no increased risk. Also, most studies have shown that the chance of getting prostate cancer is not increased by tobacco or alcohol use, BPH, a sexually transmitted disease, obesity, a lack of exercise, or a diet high in animal fat or meat. Researchers continue to study these and other possible risk factors.

Researchers are also studying how prostate cancer may be prevented. For example, they are studying the possible benefits of certain drugs, vitamin E, selenium, green tea extract, and other substances. These studies are with men who have not yet developed prostate cancer.

Dictionary Terms

A gene on chromosome 17 that normally helps to suppress cell growth. A person who inherits certain mutations (changes) in a BRCA1 gene has a higher risk of getting breast, ovarian, prostate, and other types of cancer.

A gene on chromosome 13 that normally helps to suppress cell growth. A person who inherits certain mutations (changes) in a BRCA2 gene has a higher risk of getting breast, ovarian, prostate, and other types of cancer.

Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.

The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

The complete genetic material of an organism.

A substance that is being studied in the prevention of cancer. It is made from decaffeinated green tea, and contains chemicals called catechins, which are antioxidants. Also called Polyphenon E.

Noncancerous growth of the cells lining the internal and external surfaces of the prostate gland. Having high-grade prostatic intraepithelial neoplasia may increase the risk of developing prostate cancer. Also called PIN.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

A mineral that is needed by the body to stay healthy. It is being studied in the prevention and treatment of some types of cancer. Selenium is a type of antioxidant.

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

An operation to cut or tie off the two tubes that carry sperm out of the testicles.

A nutrient that the body needs in small amounts to function and stay healthy. Vitamin E helps prevent cell damage caused by free radicals (highly reactive chemicals). It is fat-soluble (can dissolve in fats and oils) and is found in seeds, nuts, leafy vegetables, and vegetable oils. Not enough vitamin E can result in infertility (the inability to produce children). It is being studied in the prevention and treatment of some types of cancer. Vitamin E is a type of antioxidant.