A drug, called tarceva, works better in patients who were screened for a particular gene mutation. Patients with this mutation live longer than those without the mutation.

This kind of screening is easily possible and can lead to better decisions about treatment, as observed by Spanish authors of a study.

Dr. Edgardo Santos, an assistant professor of medicine in the hematology and oncology section at the University of Miami's Sylvester Comprehensive Cancer Center said, "If we are moving toward personalized medicine in the future, I think this is the way to go -- that patients be tested and use the drug if indicated."

The researchers screened 2,105 people in Spain for two different epidermal growth factor receptor gene (EGFR) mutations. The drugs, Tarceva and Iressa, seemingly show betterresults in people who have advanced non-small-cell lung cancer who also have certain mutations in the EGRF. They work by inhibiting the cancer cells' ability to multiply.

Those with mutations (16.6 percent of the sample, considered a sizable proportion) were given Tarceva. They survived more than twice as long as the rates seen in other treatment groups.

The question that arose was, "Why did people still succumb to the disease?" It was noticed that these people had developed some resistance and it is this resistance mechanism which needs to be understood now to develop counter treatment after the resistance has taken place or to develop methods which completely prevent resistance.

Tarceva is already approved for lung cancer patients who have failed at least one round of chemotherapy. It is being perceived to be a drug that can compete with systematic chemotherapy.