Castrate Resistant Prostate Cancer [CRPC] (Formerly Called Androgen Independent Prostate Cancer)
Usually, after a long period of time, prostate cancer cells will stop responding to the absence of testosterone that has been caused by ADT, and the cancer will begin growing again. It is not clear why this happens, but there are several theories.
- Some researchers believe that prostate cancer consists of many different types of cancer cells; some are killed by ADT, but others are able to survive, even thrive, on very low levels of testosterone. Eventually, those cells that survive begin to proliferate and become the dominant type of cancer cells.
- Other researchers believe that during the course of ADT some cancer cells will mutate in such a manner that they may be able to grow on lower levels of testosterone and then replicate themselves, eventually becoming the dominate cell type.
- Some believe that it is the androgen receptors on the cancer cells that mutate and become able to take better advantage of the low levels of testosterone
- There is even a theory that the cancer cells themselves find a way to produce their own, low levels of testosterone, which then enable further cancer cell growth and proliferation.
Regardless of the actual reason or reasons as to why ADT eventually fails and the cancer cells begin growing again, developing castrate resistant prostate cancer is a significant and worrisome development in the progression of your disease.
At this juncture, despite your being on ADT, your PSA will begin to climb, signaling that the cancer has begun to progress. When facing this moment, your essential first response should be to confirm that your ADT has actually achieved a castrate level (less than 20 ng/ml) of testosterone production. Testosterone levels should be monitored on a regular basis the entire time you are on ADT. If your testosterone is still at a castrate level and your PSA is climbing, you have developed castrate resistant prostate cancer (CRPC).
After developing CRPC, some doctors will recommend that you move on to chemotherapy using docetaxel (Taxotere). However, many of us believe that rather than moving to chemotherapy, this step should be delayed by either a second-line hormone therapy or an immunotherapy called Provenge, which is described later on in this guide. Despite this, a recent study from National Institute of Health (http://www.nih.gov/news/health/dec2013/nci-05.htm) showed that early chemotherapy for men with very aggressive and advanced prostate cancer can extend life.