A more precise approach to fighting cancer

Precision medicine offers a personalized approach for prevention and treatment of cancer and other diseases.

Image: © Pogotskiy/Thinkstock

If you have a stomachache or cold, you go to the pharmacy and grab the same remedy that everyone else uses, and it often works. But is that always the best approach? Your reaction to an infection may be quite different from someone else's, so perhaps you need a treatment designed just for you and your ailment.

That's the philosophy behind precision medicine (sometimes referred to as personalized medicine), an emerging approach to prevention and treatment that takes into account a person's genes, environment, and lifestyle and eliminates the one-size-fits-all approach to health care.

"As you get older, you are more likely to battle diseases and ailments, and you do not want to waste your time with trial-and-error treatments that may not work and could expose you to various side effects," says Dr. Paul Avillach, assistant professor of biomedical informatics at Harvard Medical School. "Precision medicine can help take out the guesswork."

Cancer and genes

Right now, precision medicine's greatest success is for cancer. Doctors rely on family history, lifestyle habits (like diet, exercise, and smoking), and environmental factors (such as where you grew up and where you now live) to determine if you're more likely to get certain forms of cancer. This can help create preventive strategies, like adopting a healthier diet and increasing screenings.

If you have a family history of cancer, a genetic test can help clarify whether you inherited a specific genetic mutation. This involves taking sample of either blood or saliva to look for mutations in a number of genes related to certain types of cancers.

If you are diagnosed with cancer, doctors can use genetic testing on your cancer cells in order to find the best possible drug treatment. Tumors have genetic changes that cause cancer to grow and spread, and researchers have learned that changes that occur in one person's cancer may not happen in other people with the same type of cancer.

The role of drugs

To find out more about a particular patient's cancer, doctors remove a sample of the tumor tissue in a biopsy procedure. The sample is sent to a special lab, where a machine called a DNA sequencer looks for genetic changes that may cause the cancer to grow. With this information in hand, doctors then try to match the cancer with existing drugs.

When someone takes a cancer drug, the ideal outcome is to find a drug that works on the cancer, but doesn't cause harmful side effects. "With a tumor's genetic profile, we can screen 1,000 different drugs to see which ones might work best," says Dr. Avillach.

This way, a person is less likely to receive a drug that may not work or causes severe side effects, like blood clotting. That, in turn, cuts down on the odds of having to start treatment over again with a new drug.

"While there is always the chance for some adverse effects from any drug you take, the goal with precision medicine is to minimize it as much as possible," says Dr. Avillach. So far, strategies that employ precision medicine have been used for many forms of cancer, he adds.

Moving forward

Despite its name, precision medicine is not yet as precise as it should be. A study published Oct. 19, 2017, in BMC Medical Genomics suggested that genetic targeting for cancer therapy is more accurate for people of European decent and less so for those whose ancestry is Latin American, African, or Asian. Also, genetic testing for cancer treatment is not available everywhere; it's practiced mostly at research hospitals and cancer centers.

Still, this new approach opens the door to what may be a better way of managing and treating other common age-related conditions, such as heart disease, rheumatoid arthritis, and Alzheimer's disease. "Precision medicine is only one added element in an ongoing equation," says Dr. Avillach. "It won't replace the testing and treatments currently in place, but it can help to get a more targeted answer for some."