Cancer Treatment

Genetic Testing May Help Identify Medications More Likely to Work for You

Learn why one medication works for one patient but not another

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Do you ever wonder why one medication works for one patient but not another?

The answer may lie in pharmacogenomics. This growing area of personalized medicine studies how a person’s unique genetic makeup influences his or her response to pharmaceutical drugs and medications.

“Just as our genes determine our blood type and eye color, they are partially responsible for how our bodies respond to medications,” says Dr. Maurie Markman, President of Medicine and Science for Cancer Treatment Centers of America® (CTCA). “Pharmacogenomics looks for changes in these genes that may determine whether a medication could be a viable treatment or cause specific side effects.”

What is pharmacogenomics?

The field of study works by testing genetic profiles to learn how patients may process a variety of drugs, including cancer treatments. Differences between individuals may affect drug absorption, metabolism or activity. “The one-size-fits-all approach to cancer treatment is quickly becoming a thing of the past,” says Dr. Markman. “It is being replaced with medications and treatments targeted directly to a patient’s individual DNA.”

Currently, doctors base the majority of their drug prescriptions on clinical factors, such as the cancer’s stage and the patient’s age and gender. But someone’s genetic factors may be as important as the clinical factors. For a small subset of drugs, researchers have identified genetic variations that influence how people respond. In these cases, doctors can use the pharmacogenomics information to select the medication with the best likelihood of working and identify people who need an unusually high or low dose.

Finding medications that are more likely to work for you

The U.S. Food and Drug Administration, which monitors the safety of all drugs in the United States, has included pharmacogenomics information on the labels of more than 150 medications. This information—which may cover dosage guidance, possible side effects or differences in effectiveness for people with certain genomic variations—may help doctors tailor their drug prescriptions for individual patients.

But there are limitations. Pharmacogenomics does not provide information about how patients may respond to every medication. Some may need more than one test if they are taking more than one type of medication. “The tests are not a crystal ball—they cannot determine the perfect drug for your condition or provide information on drug interactions,” says Dr. Markman. “Rather, pharmacogenomics testing can narrow down your options and help doctors prescribe the right medicine faster.”

While the use of pharmacogenomics is limited, new approaches are being studied in clinical trials. The ultimate goal is to develop tests that will lead to the development of tailored drugs to treat a wide range of health problems, including various cancers. “Precision medicine in cancer care is evolving at a fast pace,” says Dr. Markman. “Pharmacogenomics is also expected to become more standard as precision medicine becomes more commonplace.”

Learn more about precision cancer treatment.