With the diagnostic and monitoring potential of cancer genetics already being realized, researchers are now trying to develop therapies to inactivate the oncogenes that turn on tumor cells and to correct defective suppressor genes. Several approaches are being investigated.
Gene Therapy The approach that theoretically could lead to the most specific and
curative form of treatment is commonly called gene therapy. This involves replacing a defective oncogene or tumor-suppressor gene with its normal counterpart.
Since retinoblastomas, Wilms' tumors and lung, breast and colon cancers are known to be caused by genetically inactivated tumor-suppressor genes, these cancers might be obvious targets for gene therapy designed to replace abnormal tumor-suppressing genes.
Gene therapy can also take the form of inserting newly designed or foreign (recombinant) genes into bone marrow , blood, skin or other cells removed from a patient. When returned to the patient, these new genes can make therapeutic proteins.
The first attempts at gene therapy for humans were undertaken by medical investigators at the National Cancer Institute in the early 1990s. Now, investigations across the country have ongoing genetic protocols for certain cancer patients as well as non-cancer patients.
There are, however, at least three major technical obstacles that must be overcome before gene therapy will be routinely available for the treatment of human cancers:
• Tumor cells tend to reject foreign genes even after they are transferred into the cell.
