Chemotherapy
Chemotherapy is the use of powerful toxic drugs to attack cancer cells and are generally reserved for patients with advanced cases of cancer that have become resistant to hormone therapy. Chemotherapy is the use of any one or combination of cancer-killing drugs. It is prescribed in cases of advanced or recurrent prostate cancer that has not responded to hormone treatment, but it is not used to treat early stage disease.
When patients experience either hormone refractory cancer or prostate cancer bone metastasis, doctors may begin chemotherapy. Chemotherapy is given in cycles of treatment followed by a recovery period. The entire treatment generally lasts three to six months, depending on the type of chemotherapy medications given.
Chemotherapy drugs are used to shrink or slow the growth of tumors, and to find and kill cancer cells that have spread to other parts of the body. Other drugs are used to manage symptoms of advanced prostate cancer and alleviate pain.
It was previously thought chemotherapy would not work for prostate cancer. Many early chemotherapy drugs identify cancer cells through their fast rate of growth, yet prostate cancer cells grow slowly compared to most cancers. Development of chemotherapy drugs for prostate cancer is lagging behind other forms of cancer. New research is also looking at drugs and treatments for earlier intervention.
One longstanding chemotherapy treatment is Taxotere (docetaxel), a drug derived from the bark of the Pacific Yew tree. Taxotere is a chemotherapy approved for treatment of advanced prostate cancer. It is administered by injections either every three hours, every week, or every three weeks depending on the doctor’s prescriptions. Taxotere (and another chemo drug, paclitaxel) are members of the taxane group of chemotherapy that attacks prostate cancer by causing the microtubules of a cell’s cytoskeleton to become rigid. The rigidity locks the cytoskeleton in place, causing the cell to crumble and die when it tries to divide.
More work needs to be done to develop more effective chemotherapy drugs and drug combinations to combat prostate cancer, and researchers are looking to study drugs that break down cancer’s resistance to chemotherapy.
In June 2010, the Food and Drug Administration approved a new chemotherapy drug – Jevtana (cabazitaxel) which is given by injection – to treat prostate cancer that does not respond to hormone-deprivation treatments or to docetaxel, the cancer drug most commonly used to fight prostate tumors.
Jevtana was approved for use in combination with the steroid prednisone, which is often used in cancer treatment. Research shows that this therapy extended by nearly 2.5 months the lives of men with prostate tumors that resist standard treatment with hormones and other chemotherapy.
Few chemotherapy agents have been approved by the FDA specifically for use in prostate cancer. Over time, however, some medications regularly used in other types of cancers have been found to be effective in treating prostate cancer. This gives the drug an “off- label” use, meaning that drug is approved by the FDA for treating one disease yet is being used for another. Off-label use of chemotherapy is common.
Some chemotherapy medications that are commonly used off-label after docetaxel has stopped working include: vinorelbine (navelbine), paclitaxel (Taxol), cyclophosphamide (cytoxan), and etoposide (VP-16). These drugs may only work for a short period of time. For this reason, participating in a clinical trial for experimental drugs can offer new avenues for obtaining effective treatment.
