Single and multiple genetic defects associated with tumors are now being identified in clinical and laboratory research programs.
It is now possible to identify in any individual whether a specific oncogene has become activated or whether a tumor suppressor gene is defective or absent. It is likely that within a few years these genetic factors will be used routinely to determine both the diagnosis and the prognosis of people with cancer.
Since the presence of certain genetic defects may predispose some cancers to spread, genetic tests can enable physicians to identify individuals who are at higher risk for developing metastases. In these cases, more intensive clinical follow-up can then be offered or more effective adjuvant therapy can be given to improve the chance for cure.
The routine use of specific genetic tests has already begun and the new knowledge about and understanding of cancer genetics is also having an influence on cancer therapy.
Screening Techniques that test for genetic defects including activated oncogenes and abnormal tumor-suppressor genes are becoming available for use in selected situations such as detecting familial polyposis of the colon, a benign condition caused by inactivation of the APC tumor-suppressor gene that predisposes toward the development of colon cancer.
Prenatal and postnatal tests can detect abnormalities involving any of the known tumor-suppressor genes like RB that are associated with inherited forms of cancer, thereby identifying infants or children who are at risk for
