Washington ? Scientists have mapped the cascade of genetic changes that turn normal cells in the brain and pancreas into two of the most lethal cancers. The result points to a new approach for fighting tumors and maybe even catching them sooner.

Genes blamed for one person’s brain tumor were different from the culprits for the next patient, making the puzzle of cancer genetics even more complicated.

But the research also found that clusters of seemingly disparate genes all work along the same pathways. So instead of today’s hunt for drugs that target a single gene, the idea is to target entire pathways that most patients share. Think of delivering the mail to a single box at the end of the cul-de-sac instead of at every doorstep.