The exact cause of prostate cancer is unknown; however, it is clear that prostate cancer begins when cells in the prostate become abnormal. Abnormalities occur when changes or mutations in the DNA (the substance that carries instructions for each cell in the human body) of certain cells cause the cells to grow and divide more rapidly than they should. The accumulating abnormal cells form a tumor, which can be benign (non-cancerous) or cancerous. If these cells are cancerous, they can grow to invade nearby tissue. Some abnormal cells then can break off and spread (metastasize) to other parts of the body.

Researchers have found some risk factors that can affect a man’s likelihood of developing prostate cancer. They include:

  • DNA mutations that can be inherited or developed during a lifetime. Inherited DNA mutations in certain genes may cause about 5 percent to 10 percent of prostate cancers. However, most DNA changes related to prostate cancer seem to be developed during a man's life as opposed to being inherited. When a cell prepares to divide into two new cells, it copies its DNA. Sometimes errors occur during this process, leaving the flawed DNA in the new cell and creating an abnormal cell.
  • The development of prostate cancer may be linked to increased levels of certain hormones. In general, the more quickly prostate cells grow and divide, the higher the probability that mutations will occur. Therefore, anything that speeds up this process may make prostate cancer more likely. High levels of androgens (male hormones, such as testosterone) promote prostate cell growth and therefore, may contribute to prostate cancer risk in some men.
  • Inflammation may contribute to prostate cancer. Some studies have found that inflammation may lead to cell DNA damage, possibly increasing the likelihood that a cell becomes cancerous.
  • Exposure to radiation or cancer-causing chemicals may cause DNA mutations. While a possibility, there is little evidence at this time to show that radiation or cancer causing chemicals are important causes of mutations in prostate cells.