New results from the Cancer Genome Atlas research project identify a host of genetic mutations that are common among 12 different types of cancer, reflecting the growing understanding that tumors can be defined by their underlying biology rather than their location in the body.

The report, published Wednesday by the journal Nature, is part of an effort to compile a list of all genetic mutations that can trigger the development and progression of tumors. Experts hope such a list will guide diagnosis of cancer and spur development...