We still do not know exactly what causes prostate cancer. But researchers have found some risk factors and are trying to learn just how these factors cause prostate cells to become cancerous (see section, "What are the risk factors for prostate cancer?").

On a basic level, prostate cancer is caused by changes in the DNA of a prostate cancer cell. During the past few years, scientists have made great progress in understanding how certain changes in DNA can cause normal prostate cells to grow abnormally and form cancers. DNA is the chemical that carries the instructions for nearly everything our cells do. The reason that you might look like your parents is because they are the source of your DNA.

DNA affects more than the way you look. Some genes (parts of your DNA) contain instructions for controlling when cells grow and divide. Certain genes that promote cell growth and division are called oncogenes. Others that normally slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancer can be caused by DNA changes (mutations) that turn on oncogenes or turn off tumor suppressor genes.

DNA changes can either be inherited from a parent or can be acquired during a person's lifetime.

Inherited DNA mutations

Researchers have found inherited DNA changes in certain genes may cause about 5% to 10% of prostate cancers.

Several mutated genes have been found that may be responsible for a man's inherited tendency to develop prostate cancer. One of these is called HPC1 (Hereditary Prostate Cancer Gene 1). But there are many other gene mutations that may account for some cases of hereditary prostate cancer. None of these is a major cause, and more research on these genes is being done. Genetic tests are not yet available.

As mentioned above, men with BRCA1 or BRCA2 gene changes may have an increased prostate cancer risk. Mutations in these genes more commonly cause breast and ovarian cancer in women. But BRCA changes probably explain only a very small number of prostate cancers.

DNA mutations acquired during a man's lifetime

Most DNA mutations related to prostate cancer seem to develop during a man's life rather than having been inherited. Every time a cell prepares to divide into 2 new cells, it must copy its DNA. This process is not perfect, and sometimes errors occur, leaving the flawed DNA in the new cell.

It is not clear how many of these DNA mutations might be random events, and how many may be influenced by other factors (diet, hormone levels, etc.). In general, the more quickly prostate cells grow and divide, the more chances there are for mutations to occur. Therefore, anything that speeds up this process may make prostate cancer more likely.

The development of prostate cancer may be linked to increased levels of certain hormones. High levels of androgens (male hormones, such as testosterone) promote prostate cell growth, and may contribute to prostate cancer risk in some men.

Some researchers have noted that men with high levels of another hormone, insulin-like growth factor-1 (IGF-1), are more likely to get prostate cancer. IGF-1 hormone is similar to insulin, but it works on cell growth, not sugar metabolism. However, other studies have not found a link between IGF-1 and prostate cancer. Further research is needed to make sense of these findings.

As mentioned in the "What are the risk factors for prostate cancer?" section, some recent studies have found that inflammation may contribute to prostate cancer. One theory is that inflammation may lead to cell DNA damage, which might in turn push a cell closer to becoming cancerous. More research in this area is needed.

Exposure to radiation or cancer-causing chemicals may cause DNA mutations in many organs of the body, but these factors have not been proven to be important causes of mutations in prostate cells.

Last Medical Review: 07/30/2009
Last Revised: 07/30/2009