What causes prostate cancer?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

The cause of prostate cancer is unknown. The disease begins as a small bump of abnormal cells located within the prostate. These cancerous cells do not die like normal cells, and they divide at a much higher rate as well. Therefore over time, sometimes many years, the bump of abnormal cells grows larger, eventually becoming a tumor, from which the cancer can spread to other parts of the body.

Age, health and genetic factors all play a role in increasing the risk of prostate cancer. The disease is by far most common in men over age 65, and is more common among black men than any other race. Risk also increases with a history of the disease in the family. Heightened risk has been linked to certain genetic and cellular factors as well, such as the presence of a type of high-grade cell called prostatic intraepithelial neoplasia, or certain changes in genes such as BRCA 1 or BRCA2. Obesity doesn't necessarily increase the risk of the disease, but it does make its detection more difficult, meaning that when it is diagnosed it is likely to be in a more advanced state.

Causes are unknown, but potential prostate risk factors are being studied, such as tobacco use and sexually transmitted infections. Ongoing research is also investigating whether certain vitamins and supplements lower prostate cancer risks.

Other prostate cancer risk factors include:

  • Race: Studies show that African American men are approximately 60 percent more likely to develop prostate cancer in their lifetime than Caucasian or Hispanic men.
  • Family History of Prostate Cancer: Men with an immediate blood relative, such as a father or brother, who has or has had prostate cancer are twice as likely to develop the disease. If there is another family member diagnosed with the disease, the chances of getting prostate cancer increase.
  • Diet: A diet high in saturated fat, as well as obesity, increases the risk of prostate cancer.
  • High Testosterone Levels: Men who use testosterone therapy are more likely to develop prostate cancer, as an increase in testosterone stimulates the growth of the prostate gland.
  • Prostatic Intraepithelial Neoplasia (PIN): This condition may be associated with increased risk of prostate cancer. PIN is a condition in which prostate gland cells look abnormal when examined with a microscope. It is not necessarily linked with any symptoms. Nearly one half of men will be diagnosed with PIN before age 50.
  • Genome Changes: Certain genes have been known to elevate prostate cancer risks, such as BRCA1 and BRCA2 genes.

Prostate cancer is the most common non-skin cancer in men and the second-leading cause of cancer death in American men. Prostate cancer is, like all cancers, caused when normal cells lose control on replicating. The cause of this is complex, but in the case of prostate cancer, it is related to aging and the effects of testosterone. At this time, we do not have any way to prevent prostate cancer.

The three most significant risk factors for prostate cancer are having family members with prostate cancer (especially if they got it when they were young), being African American and increasing age.

Fortunately, most prostate cancer is slow growing and affects older men. Most men diagnosed with prostate cancer do not die from it.

No one knows what causes prostate cancer to develop. It becomes more common with age, is more common in some ethnic groups, such as African Americans, and is more likely to develop in men who have immediate relatives (father or brother) who have had it. In about 1 out of 10 cases, an inherited abnormal gene appears to be involved. It is also more common in some countries, such as the United States, than others, such as Japan. But when men from other countries in which the incidence is low, such as Japan, move to the United States, the rate of developing prostate cancer increases in their sons and grandsons. All this suggests that there is an interaction between genetics and environmental causes. Differences in diet have been suggested to be the primary environmental factor. But, on the other hand, there may be more prostate cancer in this country simply because it is detected more.

It is thought that potential causal factors act by altering the balance of male hormones in the body because prostate cancer is a hormone-sensitive cancer, like breast cancer. The male sex hormone, testosterone, produced by the testes influences the growth and spread of prostate cancer. Thus, higher testosterone levels or greater lifetime exposure to testosterone appears to contribute to its development. This has been used to explain the higher incidence rates in African Americans, who tend to have higher average testosterone levels than other ethnic groups or in tall men who may have had an earlier onset of higher testosterone levels.

Beginning at age 50, the risk of prostate cancer increases with age. The lifetime risk of dying from prostate cancer is 3.4 percent for American men. There is also increased risk if a male close relative (grandfather, father, or brother) has a prostate cancer.

Dr. Marc B. Garnick, MD
Hematologist & Oncologist

Regardless of the exact cause, researchers have identified several factors that increase a man's risk of developing prostate cancer:

  • Age: The risk of prostate cancer increases with age. The average onset is at age 70, and about 98 percent of cases occur in men over age 55.
  • Family history: A man who has a father, brother, or son with prostate cancer has two to three times the risk of developing the disease as a man whose first-degree male relatives don't have the disease. A man who has two or more first-degree relatives with prostate cancer faces a risk five to 10 times greater than one who has no family history of the disease.
  • Race: African American men have the highest rate of prostate cancer. Asian American and Hispanic men are less likely to have the disease than white men. Although the reasons are unclear, researchers suspect a number of variables may be involved. For example, testosterone stimulates the growth of this cancer, and on average, African American men tend to have higher levels of this hormone than men of other races. Another possibility is a particular variation in the gene involved in metabolizing testosterone. This genetic variant seems to occur more often in African Americans than in men of other races.
  • Nationality: Men in North America, northwestern European countries, Australia and the Caribbean are more likely to develop prostate cancer than men in Africa, Asia, and Central and South America. Genetic factors, as well as intensive screening efforts in some countries, may account for a bit of the disparity. But environmental and lifestyle factors, such as diet, may be responsible for the differences, too.
  • Diet: How diet influences risk isn't entirely clear, but studies have found associations between prostate cancer and the consumption of certain types of foods. For example, men who eat a lot of red meat or high-fat dairy products seem to have a higher risk of the disease. Some studies have also found that high levels of calcium (much more than what's in the average diet) seem to raise the risk. That's why experts generally recommend a diet high in fruits and vegetables and low in saturated fat.
Dr. Mark S. Litwin, MD

Causes are unknown, but there are two high-risk groups for prostate cancer. The first is men who have a family history of prostate cancer. If you have a brother or a father with a history of prostate cancer, you have a higher risk for developing the disease. Men who are of African ancestry are also at higher risk for prostate cancer. African-American men typically have a two- or three-fold higher risk of developing prostate cancer, often the aggressive type. These men ought to give serious consideration as to whether prostate cancer screening, diagnosis and treatment might be right for them.

Researchers don't know what causes prostate cancer but suspect that genetics and diet may play a role. A man's age is the biggest risk factor. In this video, William Oh, MD, an oncologist at The Mount Sinai Medical Center, discusses other risk factors.

While we do not yet know exactly what causes prostate cancer, we do know that certain risk factors are linked to the disease. The chance of getting prostate cancer goes up as a man gets older. Most prostate cancers are found in men over the age of 65. For reasons that are still unknown, African American men are more likely than white men to develop prostate cancer. Having one or more close relatives with prostate cancer also increases a man’s risk of having prostate cancer.

It is unclear as to the exact cause of prostate cancer, whether it’s genetic or environmental. Prostate cancer, similar to other cancers, begins when the cells of the prostate gland become abnormal, usually through DNA mutations. These mutations cause the cells to continuously divide and grow more rapidly than other cells.

Age is one of the most important risk factors for prostate cancer. Men over 50 years old have been shown to be at greater risk and approximately two-thirds of all prostate cancers are diagnosed in men over the age of 65.

Race also plays a role in prostate cancer risk, as African American men are more likely to get diagnosed than their white counterparts. Furthermore, African American men are more likely to present with advanced disease when diagnosed. For this reason, the urological community generally recommends PSA screening for African American men beginning at the age of 40.

Family history is also an important factor. A brother or a father with the disease can significantly increase one’s lifetime risk of prostate cancer, and this risk increases further when multiple family members are affected. Specific genes that may be responsible for prostate cancer are currently being studied, although no genetic test is widely available at this point.

High dietary fat is also suspected to increase the overall risk of prostate cancer, although the research is unclear as to the exact role it may play.

The important take-home message is that men at increased risk for prostate cancer, whether due to age, race or family history, should have a discussion about their risk profile with their primary care physician.

Exact causes are unknown, but an important risk factor is age; more than 70 percent of men diagnosed with this disease are over the age of 65. African American men have a substantially higher risk of prostate cancer than white men, including Hispanic men. In addition, dramatic differences in the incidence of prostate cancer are seen in different populations around the world.

Genetic factors appear to play a role in prostate cancer development, particularly among families in which the diagnosis is made in men under age 60.

This answer is based on source information from the U.S National Institutes of Health.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.