Colorectal cancer is one of the most commonly diagnosed cancers in the United States. Fortunately, advances in the treatment of colorectal cancer have dramatically improved survival rates.

And now, thanks to a better understanding of a gene called KRAS, researchers have developed a way to personalize treatment for some patients with metastatic colorectal cancer. 

Here are some questions and answers about personalized medicine and the role of the KRAS gene in colorectal cancer:

What is personalized medicine?

Personalized medicine is the opposite of a “one size fits all” approach. In the past, all patients with the same type and stage of colorectal cancer got the same treatment. But today, researchers know that no two patients’ tumors are exactly alike.

In the case of metastatic colorectal cancer, doctors can use information about your tumor to help them decide whether one treatment is more likely to work than another. Knowing that a treatment is not effective for you spares you the side effects related to that particular treatment.

What are biomarkers? 

Personalized medicine is made possible by the discovery of biomarkers. Biomarkers are molecular characteristics of a tumor that can be used to help make decisions about your treatment. The biomarker that is helping doctors personalize treatment for metastatic colorectal cancer is the KRAS gene.

What is the KRAS gene? 

KRAS (pronounced kay-razz) is a gene that is found to be mutated, or changed, in about 40% of people with colorectal cancer. The other 60% of people have a non-mutated (sometimes called “wild type”) KRAS gene. 

Research shows that the two drugs cetuximab (Erbitux) and panitumumab (Vectibix), often used with chemotherapy, are not effective in tumors that carry the KRAS mutation. A test known as KRAS mutation analysis, or simply “KRAS testing,” can tell whether your tumor carries this mutation.