Prostate cancer is the third leading cause of cancer deaths among men in the United States. Despite previous reports of chemotherapy's ineffectiveness in fighting prostate cancer, a number of recent medical studies are providing some hope with new cancer-fighting drugs. What is chemotherapy? What are some of the chemotherapeutic agents used to fight prostate cancer? The following information should help answer these questions.
What is the prostate?
The prostate, a part of the male reproductive system, is about the same size and shape as a walnut and weighs about an ounce. It is located below the bladder and in front of the rectum, and surrounds the urethra, the tube-like structure that carries urine from the bladder out through the penis. The main function of the prostate is to produce ejaculatory fluid.
What is prostate cancer?
Prostate cancer is a significant health care problem in the United States due to its high incidence. It is the most common cancer in men affecting approximately 234,000 American men each year with approximately 27,000 of diagnosed men dying each year. Prostate cancer is different from most cancers in that a large considerable percentage of men, particularly older men with a shorter life expectancy, may have a "silent form" of this cancer—it will not cause symptoms or spread beyond the prostate gland during their lifetime. Sometimes this cancer can be small, slow growing and present limited risk to the patient. Clinically important prostate cancers can be defined as those that threaten the well-being or life span of a man.
What is chemotherapy?
Although surgery and radiation therapy remove, destroy or damage cancer cells in a specific area, chemotherapy works throughout the body. Chemotherapy can destroy cancer cells that have metastasized, or spread to parts of the body far away from the primary (original) tumor. Chemotherapy is the use of specific drugs that can destroy cancer cells. The drugs circulate throughout the body in the bloodstream and can kill any rapidly growing cells, including potentially non-cancerous ones. Chemotherapy drugs are carefully controlled in both dosage and frequency so that cancer cells are destroyed while the risk to healthy cells is minimized. Often, it is not the primary therapy for prostate cancer patients, but may be used when prostate cancer has spread outside of the prostate gland or in combination with other therapies.
What are some of the side effects of chemotherapy?
Common side effects of chemotherapy depend on the type of drug used, dosage and length of treatment. The most common side effects are fatigue, nausea and vomiting, diarrhea, hair loss and increased susceptibility to infection. To minimize the side effects, chemotherapy drugs are carefully monitored according to the amount and number of times they are administered by your physician. Supportive medication is also given to further help offset the side effects caused by the drugs. For instance, new drugs to prevent nausea and vomiting can minimize these side effects. Most side effects disappear once chemotherapy is stopped.
How is chemotherapy administered?
The drugs used for chemotherapy can be administered directly into a vein while others may be taken orally. Some of the drugs must be given in the doctor's office or clinic; others can be administered while the patient is at home. Hospitalization is rarely needed unless side effects occur.
What are some of the new chemotherapy drugs currently being tested?
Several promising new anticancer drugs are under study and are being added to surgery or radiation therapy for men with stage III (cancer has spread to surrounding tissue or seminal vesicles) prostate cancer. Chemotherapy is also being tried in conjunction with hormone therapy for men whose advanced cancers are no longer responsive to hormonal therapy alone.
Historically, chemotherapy has not proven particularly effective against slow-growing prostate cancer cells. However recent studies show significant promise in advanced prostate cancer. There are now two published clinical trials in which men with metastatic, advanced prostate cancer progressing despite hormone therapy received a chemotherapy drug called docetaxel or mitoxantrone. In each of these trials, symptom improvement, substantial PSA reduction, and increased survival were significantly more likely to occur in the group of men who received docetaxel versus another drug called mitoxantrone. Thus the current standard of care is to use docetaxel as the first chemotherapy drug in the treatment of metastatic prostate cancer.
A number of interesting new drugs are being developed to combine with docetaxel. They include bevacizumab (Avastin), atrasentan (Xinlay) and calcitriol (DN 101) and GVAX In preliminary studies, each of these drugs, when combined with docetaxel, caused substantial PSA declines in more than 50 percent of men as well as symptomatic improvement in men with advanced disease. The four combined drug regimens are now being compared to docetaxel alone in four separate phase III clinical trials. All men with metastatic prostate cancer who are considering chemotherapy are encouraged to enter one of those 4 trials.
The encouraging results of these trials have caused the initiation of other studies investigating various chemotherapy regimens in both early and late prostate cancer. For example, there are many studies underway adding docetaxel to surgery or radiation therapy for men with stage III (cancer has spread to surrounding tissue or seminal vesicles) or high-risk prostate cancer. Other studies will determine if vaccines which induce immune responses against prostate specific targets will improve outcomes for men with advanced cancers. In addition, there are new drugs in clinical trials which will target the testosterone (androgen) signaling pathway in advanced prostate cancer, as more evidence suggests that many cancers remain sensitive to better androgen deprivation, including abiraterone, and MDV3100, both of which are new approaches to androgen deprivation.
For patients whose disease has progressed despite docetaxel chemotherapy, there are currently no FDA approved agents and participation in clinical trials is highly encouraged. Current options include best supportive care, alternative chemotherapeutic regimens, bisphosphonates (bone-strengthening agents), radiation therapy, additional hormonal manipulations, and steroids. One agent being evaluated in phase III trials is an oral form of chemotherapy called satraplatin, and while it has shown early signs of benefit in terms of delaying progression, we await more long term survival results in 2007.
Frequently asked questions:
What are the advantages and disadvantages of chemotherapy? How do I know if it's right for me?
Chemotherapy provides an additional means of relieving the symptoms of advanced prostate cancer possibly by reducing pain and slowing tumor growth. However, because chemotherapy is an aggressive treatment with side effects, it is important to discuss your treatment options with your doctor.
Can I take other medicines while I am getting chemotherapy?
Some medicines may interfere with the effects of your chemotherapy drugs. To ensure that your treatment is the most effective that it can be, tell your doctor about any and all prescription and non-prescription medicines you are taking. Your doctor will tell you if you should stop taking any of these medicines before you start chemotherapy. After your treatments begin, check with your doctor before taking any new medicines or stopping the ones you already take.
Can I continue with my normal activities while I am getting chemotherapy?
Whether you can continue work, school and other activities depends on your treatment and how it affects you. Hospitalization is not needed for the treatments and most people are able to continue their activities during treatment. You might be able to schedule your treatments late in the day or before the weekend to minimize their interference with your activities.
Reviewed March, 2007
Common misspellings: prostrate
--------------------------------------------------------------------------------
Glossary Terms
androgen:
Male sex hormone.
bladder:
The balloon-shaped pouch of thin, flexible muscle in which urine is temporarily stored before being discharged through the urethra.
cancer:
An abnormal growth that can invade nearby structures and spread to other parts of the body and may be a threat to life.
chemotherapy:
Treatment with medications that kill cancer cells or stop them from spreading.
ejaculatory:
Involved in or related to the structure involved in the release of semen from the penis during orgasm.
ejaculatory fluid:
Semen.
FDA:
Food and Drug Administration.
frequency:
The need to urinate more often than is normal.
gland:
A mass of cells or an organ that removes substances from the bloodstream and excretes them or secretes them back into the blood with a specific physiological purpose.
hormonal therapy:
Treatments that add, block or remove hormones.
hormone:
A natural chemical produced in one part of the body and released into the blood to trigger or regulate particular functions of the body. Antidiuretic hormone tells the kidneys to slow down urine production.
hormone therapy:
Treatment that adds, blocks or removes hormones.
infection:
A condition resulting from the presence of bacteria or other microorganisms.
ions:
Electrically charged atoms.
metastasized:
Cancerous tumor that has spread to another part of the body.
metastatic:
Cancer that has metastasized, in other words, spread to other parts of the body.
penis:
The male organ used for urination and sex.
prostate:
In men, a walnut-shaped gland that surrounds the urethra at the neck of the bladder. The prostate supplies fluid that goes into semen.
PSA:
Also referred to as prostate-specific antigen. A protein made only by the prostate gland. High levels of PSA in the blood may be a sign of prostate cancer.
radiation:
Also referred to as radiotherapy. X-rays or radioactive substances used in treatment of cancer.
radiation therapy:
Also referred to as radiotherapy or radiation. X-rays or radioactive substances used in treatment of cancer.
rectum:
The lower part of the large intestine, ending in the anal opening.
seminal vesicle:
Two pouch-like glands behind the bladder. They produce a sugar-rich fluid called fructose that provides sperm with a source of energy that helps sperm move. The fluid of the seminal vesicles makes up most of the volume of a man's ejaculatory fluid, or ejaculate.
stage:
Classification of the progress of a disease.
steroid:
An organic fat-soluble compound.
testosterone:
Male hormone responsible for sexual desire and for regulating a number of body functions.
tissue:
Group of cells in an organism that are similar in form and function.
tumor:
An abnormal mass of tissue or growth of cells.
urethra:
In males, this narrow tube carries urine from the bladder to the outside of the body and also serves as the channel through which semen is ejaculated. Extends from the bladder to the tip of the penis. In females, this short, narrow tube carries urine from the bladder to the outside of the body.
urge:
Strong desire to urinate.
urine:
Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.
vas:
Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.
Article reproduced from the National Institute of Health and the National Library of Health. Government information at NLM Web sites is in the public domain. Public domain information may be freely distributed and copied. For more information visit www.nih.gov. The information contained in this article is not intended to provide advice on personal medical matters, nor is it intended to be a substitute for consultation with a medical professional.