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Treatment of castrate-resistant prostate cancer
The following are treatment options for castrate-resistant prostate cancer (previously called hormone-refractory prostate cancer). The types of treatments given are based on the unique needs of the person with cancer.
Some form of hormonal therapy is usually continued even if the cancer is growing despite the hormonal therapy. If all hormonal therapy is stopped, the cancer is likely to grow very rapidly.
If a man is only taking an LHRH agonist, an anti-androgen (usually bicalutamide) will be added when there are signs of castrate-resistant growth (usually a rising PSA when the testosterone level is very low). The LHRH agonist is not stopped. The PSA will often come down for a period of weeks or months before rising again. When it rises, the anti-androgen is stopped but the LHRH is continued.
The anti-androgens abiraterone acetate (Zytiga) or enzalutamide (Xtandi) are used to treat metastatic castrate-resistant prostate cancer in men who previously received chemotherapy with docetaxel. Abiraterone acetate is also used in some cases before chemotherapy.
Chemotherapy has an important role in the treatment of castrate-resistant prostate cancer.
The most common chemotherapy drugs used to treat prostate cancer are:
- docetaxel (Taxotere)
- mitoxantrone (Novantrone)
- cabazitaxel (Jevtana)
The most common chemotherapy combinations used are:
- docetaxel and prednisone – This combination reduces pain, improves quality of life and increases survival.
- mitoxantrone (Novantrone) and prednisone (Deltasone) – This combination reduces pain and improves quality of life.
- cabazitaxel (Jevtana) and prednisone – This combination prolongs survival in castrate-resistant prostate cancer.
Radiation therapy may be offered for castrate-resistant prostate cancer, either to relieve the urinary symptoms caused by the prostate tumour or to relieve the pain of bone metastases.
External beam radiation therapy may be offered as a short course of treatment (1–10 treatments) to relieve bone pain. It is not given for 4–6 weeks after a transurethral resection of the prostate (TURP), to reduce the risk of scarring in the urethra (urethral stricture).
Radium RA 223 dichloride (Xofigo) is a type of systemic radiation drug that is injected into the bloodstream. The radiation travels through the blood to where the cancer has spread. It gives off radiation, which kills the tumour cells. Radium RA 223 may be offered to men who have castrate-resistant prostate cancer that has spread only to the bones.
Bisphosphonates are drugs that strengthen bone. A bisphosphonate is used in combination with other standard treatments for castrate-resistant prostate cancer.
The type of bisphosphonate used with castrate-resistant prostate cancer is zoledronic acid (Zometa). It decreases bone-related complications in men with prostate cancer.
A RANK ligand inhibitor is biological therapy in which a monoclonal antibody blocks the action of RANK ligand (a protein that promotes bone resorption). This helps to strengthen bone. The RANK ligand inhibitor denosumab is better than zoledronic acid by increasing the time to bone-related events in metastatic castrate-resistant prostate cancer. It has recently been approved for use in men with prostate cancer in Canada.
Transurethral resection of the prostate (TURP) may be offered for hormone-refractory prostate cancer. This type of surgery is used to relieve urinary symptoms caused by the prostate tumour (palliative surgery).
Men with prostate cancer may be offered the opportunity to participate in clinical trials. For more information, go to clinical trials.