Oncogenes as markers for early detection of cancer.

Oncogenes are formed in human tumors as a result of mutations or DNA rearrangements leading to the abnormal expression or function of proto-oncogenes. Approximately 20 different oncogenes are reproducibly activated in malignancies of several types, including breast, colon, lung, pancreatic, and thyroid carcinomas, leukemias, and lymphomas. The potential utility of these oncogenes as markers for early detection of cancer is dependent on the stage of tumor development at which they are activated, and on whether the mutated oncogenes are readily distinguished from the corresponding proto-oncogenes by assays that are sufficiently sensitive to detect precancerous lesions.