“If a certain subset of ovarian cancer appears to have the molecular commonalities of one type of lung cancer, a specific type of endometrial cancers and another subtype of breast cancer, then it may not matter where they came from when it comes to the practical question of how to treat them,” says Christopher Benz, a practicing oncologist at the University of California-San Francisco’s Carol Franc Buck Breast Care Center who worked on the study. “We should probably be treating them very similarly because the pathways that drive them are very similar,” says Benz, who worked on the breast-cancer study.

For patients with hard-to-treat cancers, the new understanding suggests new types of regimens. Perhaps, for instance, drugs used to treat ovarian cancer could fight basal- like breast cancers…

Defining cancers by molecular characteristics thus means introducing a sort of matrix management into diagnosis and treatment — adding another dimension to the existing categories, rather than replacing them.

That could prove to be as simple as a chart or computer program that lets oncologists easily match the genetic profile of each patient’s cancer to the right treatment. Or, if determining treatments turned out to require complex judgments, it could lead oncologists to specialize by molecule, or group of molecules, as well as by organ. In that case, the tensions for which matrix management is famous in business would find new medical incarnations.