One approach to individualizing patient therapy is chemosensitivity testing. Chemosensitivity assay is a laboratory test that determines how effective specific chemotherapy agents are against an individual patient's cancer cells. Often, results are obtained before the patient begins treatment. This kind of testing can assist in individualizing cancer therapy by providing information about the likely response of an individual patient's tumor to proposed therapy. Chemosensitivity testing may have utility at the time of initial therapy, and in instances of severe drug hypersensitivity, failed therapy, recurrent disease, and metastatic disease, by providing assistance in selecting optimal chemotherapy regimens.
All available chemosensitivity assays are able to report drug "resistance" information. Resistance implies that when a patient's cancer cells are exposed to a particular chemotherapy agent in the laboratory, the cancer cells will continue to live and grow. Some chemosensitivity assays also are able to report drug "sensitivity" information. Sensitivity implies that when a patient's cancer cells are treated with a particular chemotherapy agent in the laboratory, that agent will kill the cancer cells or inhibit their proliferation.
The goal of all chemosensitivity tests is to determine the response of a patient's cancer cells to proposed chemotherapy agents. Knowing which chemotherapy agents the patient's cancer cells are resistant to is important. Then, these options can be eliminated, thereby avoiding the toxicity of ineffective agents. In addition, some chemosensitivity assays predict tumor cell sensitivity, or which agent would be most effective. Choosing the most effective agent can help patients to avoid the physical, emotional, and financial costs of failed therapy and experience an increased quality of life.
Fresh samples of the patient's tumor from surgery or a biopsy are grown in test tubes and tested with various drugs. Drugs that are most effective in killing the cultured cells are recommended for treatment. Chemosensitivity testing does have predictive value, especially in predicting what "won't" work. Patients who have been through several chemotherapy regimens and are running out of options might want to consider chemosensitivity testing. It might help you find the best option or save you from fruitless additional treatment. Today, chemosensitivity testing has progressed to the point where it is 85% - 90% effective.
Listing of "Reputable" Labs USA:
These labs will provide you and your physician with in depth information and research on the testing they provide.
Analytical Biosystems, Inc., Providence, Rhode Island. Ken Blackman, PhD. Solid Tumors Only. 1-800-262-6520
Anticancer, Inc., San Diego, CA. Robert Hoffman, PhD. Solid Tumors Only. 1-619-654-2555
Oncotech, Inc., Irvine, CA. John Fruehauf, MD. Solid Tumors and Hematologics. 1-714-474-9262 / FAX 1-714-474-8147
Sylvester Cancer Institute, Miami, FL. Bernd-Uwe Sevin, MD. Solid Tumors Only. (especially GYN). 1-305-547-6875
Human Tumor Cloning Laboratory, San Antonio, TX. Daniel D. Von Hoff, MD. Solid Tumors Only. 1-210-677-3827
Rational Therapeutics Institute, Long Beach, CA. Robert A. Nagourney, MD Solid Tumors and Hematologics. 562-989-6455 http://www.rational-t.com/
Weisenthal Cancer Group, Huntington Beach, CA. Larry M. Weisenthal, MD, PhD. Solid Tumors and Hematologics. 1-714-894-0011 / FAX 1-714-893-3659 / e-mail: [email protected]
Angiogenesis & Low Dose Chemotherapy
Giving low doses of several drugs every day by mouth. There would be no needles and the side effects are expected to be mild. Unlike standard chemotherapy, which is given in high doses to kill as many cancer cells as possible, the lower-dose regimen is meant to attack the blood vessels that feed the tumor. Tumors create their own supply lines by secreting substances that stimulate the formation of new blood vessels and researchers suspect that frequent low doses of certain drugs may disrupt the growth of those new vessels, starving the tumor.
The treatment includes small daily doses of standard chemotherapy drugs and two other drugs that have been found to inhibit the formation of new blood vessels, called angiogenesis. One is Celebrex and the other is Thalidomide. It is offered only to people who have no other options, who have advanced tumors that standard treatment cannot cure or those for whom standard chemotherapy has quit working.
Women with advanced breast or ovarian cancer are being given smaller, more frequent doses of chemotherapy to reduce side effects. It is hoped that low-dose treatment may help other cancer patients, not just those who are considered terminal. It may work just as well or even better, maybe through this ability to cause an anti-angiogenesis effect.
This approach to treatment is based on something that can frequently occur in people, when a tumor becomes resistant to chemotherapy and high doses stop working. It is believed that angiogenesis plays a role. Angiogenesis is essential to the survival of many tumors. Many chemotherapy drugs, in addition to killing tumor cells, also fight angiogenesis. But, if these medicines stop angiogenesis, chemotherapy should work better than it does. Blood vessel cells are less likely than tumor cells to become resistant to chemotherapy, so if cancer cells become drug resistant, these medicines should still be able to shrink tumors by destroying their blood supply.
The reason chemotherapy was not stopping angiogenesis was that chemotherapy is usually given in big doses, with breaks of several weeks between doses to let the body recover. During the breaks, the tumor's blood vessels could grow back. By giving chemotherapy more often, at lower doses, it might prevent the regrowth of blood vessels and kill the tumor or at least slow its growth.
It is especially important to study low-dose therapies now because they are being used increasingly in clinics. Doses, timing and combinations all need to be worked out. Doctors need to find out whether the treatments can make patients live longer and whether tumors will eventually outsmart the drugs and find ways to survive even without angiogenesis.
For further information about clinical trials, refer to the National Cancer Institute's website: (http://cancertrials.nci.nih.gov)
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