NEW YORK (AP) – In the largest effort of its kind, scientists have identified 26 genes that, when damaged, appear to promote lung cancer. It's a step toward developing new treatments that can be tailored to specific patients.

The federally funded project was the largest ever to screen genes for mutations in the most common form of lung cancer, called adenocarcinoma. The results more than double the catalogue of genes implicated in that condition.

The findings, from scientists at a dozen institutions in the US and Germany, appear in today's issue of the journal Nature. Lung cancer is the leading cancer killer in the United States and worldwide.

The study focused on tumours that originated in the lung and were surgically removed. But researchers also hope to study whether the same mutations appear in lung tumours that spread elsewhere.

They examined the makeup of 623 genes to look for those that were the most often mutated. The idea is that if a gene is mutated in so many tumours, it probably plays a role in the disease. The mutations clearly arose in the cancers because they did not appear in healthy tissue from the cancer patients.