Sen. Edward M. Kennedy, known as the "liberal lion of the Senate," and the last surviving brother of a fabled political dynasty, died late Tuesday at his home in Cape Cod after a year-long struggle with a malignant brain tumor.

Researchers have mapped the genetic blueprint of two of the deadliest forms of cancer, detailing the mutations that lead to tumors of the pancreas and brain.

By PBS News Hour

Sen. Edward Kennedy was diagnosed with a malignant brain tumor, his doctors said Tuesday. Malignant gliomas, like Kennedy's, are the most common type of adult brain cancers, inflicting some 9,000 Americans a year. A medical expert discusses treatment for brain…