A more precise approach to fighting cancer

If you are like me, when you get the flu you head straight to the pharmacy and grab the most powerful over-the-counter medicine you can find. But is that really the best approach? After all, your condition, symptoms, and reaction to the virus may be quite different from someone else's, so why use the same medicine? Instead, you may benefit more from a treatment specifically designed just for you and your ailment.

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

"As you get older, you are more likely to battle diseases and ailments, like cancer, 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."

The principle behind precision medicine

It works like this: 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 a sample of either blood or saliva to look for mutations in several genes related to certain cancers.

If you are diagnosed with cancer, doctors can use genetic testing on tumors 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 the changes that occur in one person's cancer may not happen in other people with the same type of cancer.

For genetic testing of tumors, doctors remove a sample of the tumor tissue and 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.

"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.

Practical applications of precision medicine still evolving

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. Another downside: genetic testing for cancer treatment is practiced mostly at larger research hospitals and cancer centers and thus is not available everywhere.

Still, for some, it can offer a better way to prevent and treat possible cancer.

"Precision medicine is only one added element in an ongoing equation," adds Dr. Avillach. "It's not the solution to everything, and it won't replace the testing and treatments currently in place, but it can help to get a more targeted answer for some."