Types of prostate cancer
The prostate has various functions, including:
- producing the fluid that nourishes and transports sperm
- secreting prostate specific antigen (PSA), a protein that helps semen retain its liquid state
- helping aid urine control
It is not clear what causes prostate cancer. Prostate cancer starts when cells in the prostate become abnormal due to mutations in the abnormal cells’ DNA that causes the cells to grow and divide more rapidly and out of control compared to what normal cells do. The abnormal cells continue living and dividing, when other cells usually die to be replaced. The accumulating abnormal cells forms the tumor that can grow to invade nearby tissue. Some abnormal cells can also break off and spread (metastasize) to other parts of the body.
Almost all prostate cancers are adenocarcinomas. These cancers develop from the gland cells (the cells that make the prostate fluid that is added to the semen).
Other types of cancers that can arise from the prostate include:
- Small cell carcinomas
- Neuroendocrine tumors (other than small cell carcinomas)
- Transitional cell carcinomas
These other types of prostate cancer are rare.
Some prostate cancers grow and spread quickly, but most grow slowly. In general, prostate cancers, unlike other cancers, have a long mean sojourn time, meaning the cancer cells divide slowly and spreads slowly. In fact, autopsy studies show that many older men (and even some younger men) who died of other causes also had prostate cancer that never affected them during their lives. In many cases, neither they nor their doctors even knew they had it.
For this, prostate cancer is considered the poster-boy example of a scrutiny-dependent cancer. Not all prostate cancers are fatal. But it is difficult to differentiate the ones that may be fatal from the ones that will not.
There are often no symptoms during the early stages of prostate cancer, but screening can detect changes that can indicate cancer.
Prostate cancer screening involves a rectal examination of the prostate and a blood test that measures levels of PSA in the blood. PSA is very specific to the prostate, but not necessarily cancer-specific. High levels of PSA suggest that cancer may be present. To confirm this, a prostate biopsy has to be done.