A risk factor is anything that increases your chance of developing a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lungs, mouth, throat, larynx, bladder, and several other organs. But having a risk factor, or even several, does not mean that you will get the disease.
Many people with one or more risk factors never develop cancer, while others with this disease may have no known risk factors. It is important, however, that you know about risk factors so that you can try to change any unhealthy lifestyle behaviors or can choose to have the early detection tests for a potential cancer.
Although we don’t yet completely understand the causes of prostate cancer, researchers have found several factors that increase the risk of developing this disease.
The chance of having prostate cancer increases rapidly after age 50. About two thirds of all prostate cancers are diagnosed in men over the age of 65. It is still unclear why this increase with age occurs.
Prostate cancer occurs about 60% more often in African-American men than in white American men. Compared with men of other races, African-American men are more likely to be diagnosed at an advanced stage. African-American men are more than twice as likely to die of prostate cancer as white men.
Prostate cancer occurs less frequently in Asian men than in whites. Hispanic men develop prostate cancer at similar rates as white men. The reasons for these racial differences are not clear.
Prostate cancer is most common in North America and northwestern Europe. It is less common in Asia, Africa, Central America, and South America. The reason for this is not well understood, but we know that is not simply due to better screening in North America and Europe.
Prostate cancer seems to run in some families, suggesting an inherited or genetic factor. Having a father or brother with prostate cancer more than doubles a man’s risk of developing this disease. (The risk is higher for men with an affected brother than for those with an affected father.) The risk is much 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 (see next section), 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 may also increase prostate cancer risk in some men, but they are responsible for a very small percentage of prostate cancer cases.
Men who eat a lot of red meat or who have a lot of high-fat dairy products in their diet appear to have a slightly higher chance of developing prostate cancer. These men also tend to eat fewer fruits and vegetables. Doctors are not sure which of these factors is responsible for increasing risk.
Some studies have suggested that men who consume a lot of calcium (through diets or supplements) may have a higher risk of developing advanced prostate cancer. Most studies, however, have not found such a link with the levels of calcium commonly consumed in the average diet, and it’s important to note that calcium is known to have other important health benefits.
Several substances, including lycopenes (found in high levels in some fruits and vegetables, such as tomatoes, pink grapefruit, and watermelon), vitamin D, vitamin E, and the mineral selenium may lower prostate cancer risk. Studies are now underway to assess whether these substances actually reduce risk.
Until such studies are completed, the best advice to lower prostate cancer risk is to eat fewer red meats and high-fat dairy products and to eat 5 or more servings of vegetables and fruits each day. This may also reduce the risk of several other cancers, as well as other health problems such as heart disease.
Some earlier studies suggested that men who have had a vasectomy (surgery to make men infertile) may have a slightly increased risk for prostate cancer, but this link has not been consistently found. Among the studies that noticed an increase in risk, some found this risk to be highest in men who were younger than 35 when they had a vasectomy.
Research to resolve this issue is still in progress. However, most recent studies have not found any increased risk among men who have had this operation, and fear of an increased risk of developing prostate cancer should not be a reason to avoid a vasectomy.