Advances in genetic research are transforming cancer diagnosis, and treatments that are tailored to the specific molecular changes that drive tumor growth are now being developed. Because most cancers result from several genetic mutations, NCI is focusing on developing diagnostic tests that identify a number of genetic markers that can be used to predict a person's response to specific therapies and inform treatment decisions for these diseases.

Molecular diagnostics is a new approach to understanding the biology of cancer.  It offers the ability to characterize the genes, proteins and biochemical pathways within a cancer cell. Using molecular diagnostics to define the genetic profiles of cancers has been a pivotal development in the delivery of more effective treatments for cancer. For some cancers, clinicians can select the most effective therapy based on the specific genes expressed in a patient’s tumor.