What are the risk factors for prostate cancer?

On a basic level, prostate cancer is caused by changes in the DNA of a normal prostate cell. DNA makes up our genes, which control how cells behave. DNA is inherited from our parents. We often look like our parents because they are the source of our DNA. But DNA affects more than how we look. A small percentage (about 5% to 10%) of prostate cancers are linked to inherited DNA changes. Other DNA changes happen during a person's lifetime. Certain of these changes can cause prostate cancer.

Inherited DNA changes (mutations)

Several mutated (changed) genes have been found that may be linked to a man being more likely to have prostate cancer. One of these is called HPC1 (Hereditary Prostate Cancer Gene 1). But there are many other gene changes that may account for some cases of hereditary prostate cancer. None of these is a major cause, and more research on these genes is being done.

DNA changes that take place during a man's lifetime

Most DNA changes related to prostate cancer seem to happen during a man's life rather than having been inherited. Every time a cell prepares to divide into 2 new cells, it must copy its DNA. This process is not perfect, and sometimes mistakes happen, leaving the flawed DNA in the new cell. It is not clear how many of these DNA changes (mutations) might be random events and how many may be linked to other factors (diet, hormone levels, etc.). As a rule, the more quickly prostate cells grow and divide, the more chances there are for mutations to occur. Therefore, anything that speeds up this process may make prostate cancer more likely.

Prostate cancer may be linked to higher levels of certain hormones. High levels of male hormones (androgens) such as testosterone may play a part in prostate cancer risk in some men. Some studies have found that men with high levels of a hormone called IGF-1 are more likely to get prostate cancer, too. But others have not found such a link. More research is needed to make sense of these findings.

Risk factors for prostate cancer

While we do not yet know exactly what causes prostate cancer, we do know that certain risk factors are linked to the disease. A risk factor is anything that increases a person's chance of getting a disease. Different cancers have different risk factors. Some risk factors, such as smoking, can be changed. Others, like a person's age or family history, can't be changed.

But risk factors don't tell us everything. Many people with one or more risk factors never get cancer, while others with this disease may have had few or no known risk factors. For some of these factors, the link to prostate cancer risk is not yet clear.

Age: Prostate cancer is very rare in men younger than 40. The chance of getting prostate cancer goes up quickly after a man reaches age 50. Almost 2 out of every 3 prostate cancers are found in men over the age of 65.

Race: Prostate cancer is more common in African-American men than in men of other races. African-American men are also more likely to have a more advanced disease when it is found and are more likely to die of the disease. Prostate cancer occurs less often in Asian-American and Hispanic/Latino men than in non-Hispanic whites. The reasons for these racial and ethnic differences are not clear.

Nationality: Prostate cancer is most common in North America, northwestern Europe, and a few other places. It is less common in Asia, Africa, Central and South America. The reasons for this are not clear. More screening (testing of people who don't have any symptoms) in some developed countries may account for at least part of this difference, but other factors are likely to be important, too.

Family history: Prostate cancer seems to run in some families. Men with close family members (father or brother) who have had prostate cancer are more likely to get it themselves, especially if their relatives were young when they got the disease. (The risk is higher for men who have a brother with the disease than for those with an affected father.)

Genes: Scientists have found some inherited genes that seem to raise prostate cancer risk, but they probably account for only a small number of cases overall. Genetic testing for most of these genes is not yet available, and more study is needed in this area.

Diet: The exact role of diet in prostate cancer is not clear, but some factors have been studied. Men who eat a lot of red meat or high-fat dairy products seem to have a greater chance of getting prostate cancer. These men also tend to eat fewer fruits and vegetables. Doctors are not sure which of these factors causes the risk to go up.

Some studies have found that men who consume a lot of calcium or dairy foods may have a higher risk of advanced prostate cancer. But most studies have not found this link with the levels of calcium found in the average diet.

Obesity: Most studies have not found that being obese (very overweight) is linked with a higher risk of getting prostate cancer. Some studies have found that obese men may be at greater risk for having more advanced prostate cancer and of dying from prostate cancer, but not all studies have found this.

Smoking: Most studies have not found a link between smoking and the risk of getting prostate cancer. A recent study linked smoking to a possible small increase in the risk of death from prostate cancer, but this is a new finding that will need to be confirmed by other studies.

Infection and inflammation of the prostate: Some studies have suggested that prostatitis (inflammation of the prostate gland) may be linked to an increased risk of prostate cancer, but other studies have not found such a link. Some researchers have also looked at whether sexually transmitted diseases (STDs) might increase the risk of prostate cancer. So far, studies have not agreed, and no clear links have been made.