Many Mutations Found in Colon, Breast Cancer

Scientists mapping the genetics of two of the nation’s leading cancers have found almost 200 mutated genes in breast and colorectal tumors, many of them never before suspected of helping cancer form and spread.

Doctors have long known it takes a cascade of genetic flaws to trigger any of the myriad types of cancer. Which genes are working improperly also determines if a malignancy is especially aggressive, and even whether a particular treatment is likely to work.

Finding those genes-run-amok could lead to better cancer treatments and even ways to prevent tumors. But scientists have found only a fraction of them.

Now, armed with better technology, a quest is beginning to comprehensively map the genetic makeup of different cancers.

On Thursday, scientists at Johns Hopkins University had their first big success reported in the online version of the journal Science: They examined more than 13,000 genes in 11 different breast tumors and 11 colorectal cancers removed from patients during surgery. They found 189 mutated ones that seem to play a role in those two types of cancer.

The number of potential culprits was surprising; researchers had expected to find a few, not dozens.

Importantly, the work emphasizes that cancers differ greatly from organ to organ: Mutations in the breast tumors were substantially different from those in the colorectal tumors.

Now the harder work begins: figuring out exactly what those altered genes do, and whether there are ways to target them.