What causes prostate cancer?
No one knows precisely what causes prostate cancer. But that doesn’t mean it’s a total mystery, either. Genetic defects play a role in the development of any cancer, as do carcinogens (substances that cause DNA damage). In some instances, the defects are inherited, meaning they affect DNA in a parent’s sperm or egg cells (also called germ cells) and carry through into a developing baby. These inherited (or germline) defects will be present in every cell of the body, but their cancer-causing effects tend to be selective for specific organs, including the prostate.
For example, germline defects in the BRCA genes that boost the risk of breast and ovarian cancer in women have also been linked to aggressive, hard-to-treat prostate cancers that affect younger men. BRCA genes ordinarily repair DNA damage. When those genes are defective, DNA damage can accumulate inside cells that, in turn, grow abnormally and form tumors. Roughly a quarter of all men who have aggressive prostate cancer have defects in one or both of the BRCA genes (BRCA1 and BRCA2), but most commonly in BRCA2 alone. Men who carry a BRCA2 mutation have a risk of prostate cancer that’s two to five times higher than the general population.
However, DNA repair defects aren’t limited to BRCA: investigators have found dozens of inherited mutations affecting other genes that could potentially be involved in prostate cancer. Indeed, more than 50% of prostate cancer risk can be attributed to genetic factors. Fortunately, many gene defects that have been found so far in advanced prostate cancer can be targeted with existing drugs or drugs that are now in clinical trials.