Flaw Seen in Genetic Test for Breast ...

Flaw Seen in Genetic Test for Breast Cancer Risk

There are 2 comments on the New York Times story from Mar 21, 2006, titled Flaw Seen in Genetic Test for Breast Cancer Risk. In it, New York Times reports that:

The widely used genetic test for breast cancer risk can miss mutations that help cause the disease, according to a new study, a finding that is likely to increase the pressure to develop more thorough testing ...

Join the discussion below, or Read more at New York Times.

gdpawel

Philadelphia, PA

#1 Mar 24, 2006
What's being left out of this report is the fact that a chemo-induced gene mutation can happen when the original chemo received does not work. The cancer comes back. When it does this, the cancer comes back more aggressively. The mutagenic effects (changes in form) of chemotherapy on a genetically-unstable tumor, drives the tumor into a state of more aggressive behavior. You might kill off a whole lot of cancer, only to cause a mutation in the remaining cancer, such that the remaining cancer behaves in a more aggressive fashion (like when chemotherapy on an ER+ cancer brings about a remission, but in the process also causes any remaining cancer to become ER-).

Conventionally, oncologists rely on clinical trials in choosing chemotherapy regimens. But the statistical results of these population-based studies might not apply to an individual. For many cancers, more than one standard treatment exists. There is rarely a situation where you would get everyone to agree that there's only one form of therapy. Physicians select drugs based on their personal experience, possible side effects and the patient's condition, among other factors. The system is overloaded with drugs and underloaded with wisdom and expertise for using them.

One approach to individualizing patient therapy is chemosensitivity testing (assay testing). It is a laboratory test that determines how effective specific chemotherapy agents are against an individual patient's cancer cells. 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 assay tests 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. However, some chemosensitivity assays go further and 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 and mutagenic effects. 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.
ukbg yg

Los Angeles, CA

#2 Feb 1, 2012
All available assay tests 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. However, some chemosensitivity assays go further and 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 and mutagenic effects. 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.

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