“Biomarker” is a general term for anything that doctors are looking for when they do a blood test or almost any other kind of diagnostic test. For example, some pregnancy tests are performed on blood and others on urine, but in either case, they are looking for the same biomarker, namely human chorionic gonadotropin, a hormone that increases rapidly during early pregnancy, but which is present in men and nonpregnant women only at levels too low to be detected by the tests. Many different compounds are higher in the blood of cancer patients than of cancer-free people; these compounds are called tumor markers, and they include a wide variety of carbohydrates, proteins, conjugated proteins, and peptides. Different tumor markers are associated with different cancers.