What is a risk factor?

A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases, including cancers, have different risk factors.

Although these factors can increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop cancer, while others develop cancer and have no known risk factors.

Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.

What are risk factors for prostate cancer?

In general, all men are at risk for prostate cancer. However, there are specific risk factors that increase the likelihood that certain men will develop the disease, including the following:

Age

Age is a risk factor for prostate cancer, especially men age 50 and older. More than 70 percent of all prostate cancers are diagnosed in men over the age of 65.

Race

Prostate cancer is nearly twice as common among African-American men than it is among Caucasian-American men. Japanese and Chinese men native to their country have the lowest rates of prostate cancer. Interestingly, when Chinese and Japanese men immigrate to the US, they have an increased risk and mortality rate from prostate cancer, when compared to their native populations. In Japan, the incidence of prostate cancer has increased as Western diets and lifestyles have been adopted.

Diet

Epidemiological data suggests that the diet consumed in Western industrialized countries may be one of the most important contributory factors for developing prostate cancer. Consider the following information regarding diet and its effect on the risk for prostate cancer:

• Fat

  Studies suggest that men who eat a high-fat diet may have a greater chance of developing prostate cancer.

• Fiber

  Dietary fiber intake may influence circulating levels of testosterone and estradiol, which, in turn, may decrease the progression of prostate cancer.

• Soy Protein

  Besides lower fat intake, another major difference between Asian and American diets is the consumption of soy, averaging 35 g a day per capita. Soy contains isoflavones which, in several studies, have been found to inhibit the growth of prostate cancer.

• Vitamin E and selenium

  Vitamin E, an antioxidant, combined with selenium, has been shown to inhibit tumor growth in laboratory animals.

• Carotenoids

  Carotenoids containing lycopenes have been shown to inhibit the growth of human prostate cancer cells in tissue cultures (cells grown in the laboratory). The primary source of lycopenes is processed tomatoes in tomato juice and tomato paste.

• Herbal preparations

  Combination herbal preparations should be used with caution as reported side effects have included venous thrombosis, breast tenderness, and loss of libido. Many herbal preparations have not been studied in men with prostate cancer.

• Obesity

  Obesity not only contributes to diabetes and high cholesterol, but has also been associated with some common cancers, including hormone-dependent tumors such as prostate, breast, and ovarian cancer.

Environmental exposures

Some studies show an increased chance for prostate cancer in men who are farmers, or those exposed to the metal cadmium while making batteries, welding, or electroplating. Additional research is needed in this area to confirm whether this is a true association.

Having a vasectomy, BPH (benign prostatic hyperplasia), or STD (sexually transmitted disease)

Researchers have looked at whether men who have had a vasectomy, BPH, or those who have been exposed to a sexually transmitted disease are at increased risk for prostate cancer. Some studies suggest a link, while others do not support these claims.

Family history of prostate cancer

• sporadic

  Sporadic means 'occurs by chance'; such as a family with prostate cancer present in one man, at a typical age of onset.

• familial

  A family with prostate cancer present in more than one person, but with no definitive pattern of inheritance and usually an older age of onset.

• hereditary

  A family with a cluster of three or more affected relatives within any nuclear family (parents and their children), a family with prostate cancer in each of three generations on either the mother or father's side, or a cluster of two relatives affected at a young age (55 or less). Five percent to 10 percent of prostate cancer cases are considered hereditary.

• genetic factors

  In the center of each cell of the human body, our genetic material - chromosomes - are found. Normally, cells contain 46 chromosomes, or 23 pairs, half of which are inherited from our mother, half from our father. The chromosomes contain the body's blueprint, our genes. Genes code for traits such as eye color and blood type, and also control important regulatory functions in the body such as the rate of cell growth. Some genes, when altered or mutated, give a higher risk for uncontrolled cell growth, which, in turn, can lead to tumor development. These genes have various names, but overall are referred to as "cancer susceptibility genes." Approximately 9 percent of all prostate cancers and 45 percent of cases in men younger than age 55 can be attributed to a cancer susceptibility gene that is inherited as a dominant trait (from parent to child).

Contributing factors to prostate cancer include age, race, diet, weight, and family history.

Five percent to 10 percent of prostate cancer cases are considered hereditary. However, the majority of cases are sporadic (occur by chance).

Approximately 9 percent of all prostate cancers and 45 percent of cases in men younger than age 55 can be attributed to a cancer susceptibility gene that is inherited as a dominant trait (from parent to child).