Dr. Nicole Urban of the Fred Hutchinson Cancer Research Center talks about the "holy grail" of biomarker research and explains the clues to cancer that doctors seek in patients.

Dr. Janet Woodcock, chief medical officer of the Food and Drug Administration, discusses how cancer biomarkers may change cancer screening and treatment.

Biomarkers, changes in a protein that indicate the progression of a disease, hold promise for different fields of medicine. NewsHour health correspondent Susan Dentzer reports on the use of biomarkers in the early detection of cancer.