The idea of matching a particular treatment to a particular patient is not a new one. It has long been recognized, for example, that hormonal therapy for breast cancer is most likely to be effective when breast cancer contains receptors for estrogen and/or progesterone. Testing for these receptors is part of the standard clinical work-up of breast cancer.

What is new, however, is the pace at which researchers are identifying new tumor markers, new tests, and new and more targeted drugs that individualize cancer treatment. Tests now exist that can assess the likelihood of cancer recurrence, the likelihood of response to particular drugs, and the presence of specific cancer targets that can be attacked by new anti-cancer drugs that directly target individual cancer cells.