The prostate is a male sex gland located underneath the bladder. It is about the size of a walnut and fits around the tube (the urethra) which carries urine out of the bladder. The prostate produces a thick fluid that forms part of the semen.
Prostate cancer differs from most other cancers in the body, because small areas of cancer within the prostate are very common and may stay dormant for many years.
About one-third of men over the age of 50 have some cancer cells within their prostate and nearly all men over the age of 80 have a small area of prostate cancer. Most of these cancers grow extremely slowly and so, particularly in elderly men, will never cause any problems.
In a small proportion of men, the prostate cancer does grow more quickly and in some cases may spread to other parts of the body, particularly the bones.
Although Everyman scientists have made progress in prostate cancer research, little is known about the genes and molecular mechanisms which cause prostate cancer. We still do not fully understand what causes this disease, or how it develops - and we urgently need to improve on current treatments.