There is no known exact cause of prostate cancer.  Doctors often cannot explain why one man develops prostate cancer and another does not. However, research has shown that men with certain risk factors are more likely than others to develop prostate cancer.
 

• Age Age is the main risk factor for prostate cancer. More than 70 percent of all prostate cancers occur in men over 65. Beginning at 50, you should have a prostate exam every year.
• Family history A man's risk is higher if his father or brother had prostate cancer. Men with a first-degree relative diagnosed with prostate cancer are considered high risk, and should begin screenings at age 40.
• Race African-American males over 40 have the highest rate of prostate cancer and should begin screenings at age 40. 
• Certain prostate changes Men with cells called high-grade prostatic intraepithelial neoplasia may be at increased risk for prostate cancer. 
• Diet Some studies suggest that men who eat a diet high in animal fat or meat may be at increased risk for prostate cancer. Men who eat a diet rich in fruits and vegetables may have a lower risk.

Talk to your doctor if you think you may be at risk. Your doctor may be able to suggest ways to reduce your risk and can plan a schedule for regular checkups.