More than 1.2 million people are diagnosed with lung cancer worldwide each year, and more than 1 million die of the disease. Ninety percent of cases occur in smokers or former smokers with only 10 percent occurring in nonsmokers. Adenocarcinoma, the type of lung cancer in the study, is the most common variant, accounting for 40 percent of lung cancer cases.
The researchers looked at tumors from 188 patients, comparing their genetic code to normal lung tissue. They found 1013 different mutations clustered in 26 genes, all but six of which had never been linked to lung cancer before.
The research, part of the Tumor Sequencing Project funded by the National Human Genome Research Institute, was published this week in Nature.
The type of genetic mutations the researchers found are called somatic mutations. They are not present at birth and are not inherited or passed on to children, but instead develop over the course of a person's lifetime.
"Somatic mutations are important because the mutated genes can be targets for anti-cancer therapy," study coauthor Matthew Meyerson, of the Massachusetts Institute of Technology, said in a teleconference, according to Voice of America. "The reason is that the cancer gene is now different from the normal gene and so some drugs can now specifically kill cells with the mutated cancer gene."
Some of the 26 genes, in fact, are part of genetic pathways that had already been linked to other cancers, and are the targets of drugs already on the market or in development.
About half of the tumors, for example, had mutations in a pathway called p53, which is important for suppressing tumor growth. Several pharmaceutical companies are already working on drugs that target this pathway.
Most of the tumors studied had many different mutations. Tumors from smokers had far more -- as many as 49 -- while tumors from nonsmokers had no more than five.
Meyerson said that genetic tests could help determine which patients would benefit from drugs already on the market, but that it will also be necessary to develop new drugs.
"Probably we will need a lot more drugs," he said, according to Reuters. "What's great is we've identified many new drug targets."
Still, there is a long research road between discovering new drug targets and actually developing effective drugs, and study coauthor Richard Wilson, of Washington University in St. Louis, says he is not certain that pharmaceutical companies will be willing to take on the necessary research.
"My sense is too often they're more focused on headache drugs than cancer drugs," he told New Scientist.