Traditionally, lung cancer has been classified into two major types: small cell and non-small cell. Today, however, lung cancer is understood to be comprised of several distinct sub-types, each characterized by mutated genes and abnormal proteins that can increasingly be kept in check by targeted therapies.
A targeted therapy is a treatment specifically designed for a specific mutation or other abnormality. In addition to being more effective than traditional chemotherapy drugs and radiation therapy at slowing a cancer’s growth and spread, targeted therapies often have fewer side effects and minimize damage to normal, healthy cells.
For example, young people and non-smokers with lung cancer commonly have mutations in a gene called EGFR. Patients who test positive for that mutation respond better to the targeted therapy Tarceva than standard chemotherapy. Young people and non-smokers with lung cancer also frequently have mutations in the ALK and ROS1 genes, which respond well to a new targeted drug called Xalkori.
Oxnard says than half of all young lung cancer patients have a mutation in their tumors for which a drug exists to block the mutation’s actions. This was not the case for either Taylor or Nunez, both of whom were successfully treated—for now—with a standard course of chemotherapy to stay the disease.
“Just bad luck, I guess,” Nunez says.
But surely it is more than that. Some researchers suspect a hereditary base to the disease’s development, as is the case in some patients with breast or colon cancer. Others suspect the cause lies in a genetic susceptibility combined with other factors, including hormonal changes or exposure to cancer-causing substances, such as radon or second-hand smoke.
Still, “the answer is that we really don’t know why people with seemingly no risk factors get lung cancer,” Oxnard said. “In the young, we are even more confused when someone that hasn’t smoked and hasn’t even been alive long enough to be exposed to anything toxic gets lung cancer.”