Scientists do not know what causes prostate cancer. Some think it starts with small changes that occur in the prostate gland’s structure, called prostatic intraepithelial neoplasia (PIN). PIN begins when men are in their 20s, and almost half of men have the condition by age 50. If PIN is a factor in prostate cancer, it helps explain why the risk of tumors increases with age.

Scientists cite several factors that may play a role in causing prostate cancer:

• Age. More than 65 percent of all prostate cancers are diagnosed in men over age 65 and older, according to the American Cancer Society (ACS).
  
  
• Family history. Having a brother or father who has prostate cancer more than doubles a man’s risk. If the family member developed the disease while younger, this increases the risk.
  
  
• Genetic mutations. Alterations in DNA that develop during a man’s life or are inherited from a parent and present at birth. Researchers have identified several gene mutations that make some men more prone to prostate cancer. Genetic tests for these alterations are not yet available for general use. Genetic mutations may account for 5 to 10 percent of prostate cancers, according to the Centers for Disease Control and Prevention (CDC).
  
  
• Race. African Americans have a 60 percent higher risk than white and Hispanic Americans. Asian Americans have below-average risk. Recent studies have identified several genes that occur more often in men with prostate cancer and those genes are also seen more often in African American men.
  
  
• Diet. A fatty diet rich in meat (especially red meat) and high-fat dairy appears to increase the risk.  Studies have also shown that barbecued meat produces a compound that may encourage the growth of prostate cancer cells.  Men with high cholesterol levels, particularly if they were detected before the age of 50, may have an increased risk as well.  Other studies show that men who take cholesterol-lowering medications called statins are less likely to have advanced prostate cancer. The connection is not well established, but cholesterol affects creation of testosterone, which may promote the growth of prostate cancer.
  
  
  
• Exercise. Although not conclusive, recent studies have indicated that men over the age of 65 who exercised regularly had a lower risk of prostate cancer. Lack of exercise can contribute to obesity, another factor that places a man at higher risk for the disease. In addition, studies show that obese men with prostate cancer are more likely to die from the disease than healthy weight men.
  
  
• Hormones. Studies have shown that higher levels of male hormones (androgens) may increase the risk of prostate cancer in certain men. Other hormones have been linked to a higher risk but additional research is necessary.