When dealing with radiation, the question of causing or promoting new cancers always arises. Sufficient doses of radiation can produce cancer in time. In using radiation therapy or any other treatment, one must always weigh the risks against the benefits. The potential benefit of using radiation therapy to cure a cancer obviously outweighs any risk of possibly causing another cancer at some future date. For example, Hodgkin’s disease patients who receive radiation therapy do have a slightly higher incidence of leukemia, but many more live longer because of the treatment, and the benefits derived vastly outweigh die potential risks.
Of course, the fear of X rays’ causing cancer is not limited to high-dose radiation therapy; even diagnostic procedures such as mammograms to detect breast cancer or chest X rays have been questioned because of their cancer-causing potential. Although no X-ray procedure should be performed routinely unless there is definite benefit to be gained, one should remember that the risk involved in these procedures is negligible when very low doses are used, as is the case in mammography using modern X-ray equipment.
The Future of Radiation Therapy
As in all rapidly advancing scientific endeavors, we can say without exaggeration that part of the future of radiation therapy is already here. Radiation therapy has been greatly advanced into a much more precise discipline by the introduction of computer technology. In fact, most radiation therapy departments are now being equipped with treatment computers that get information directly from diagnostic computers.
The improvement in diagnosis and locating a tumor has also made radiation therapy more precise and effective. We can now construct treatment plans with a precision that was unknown just a decade ago, and even more precise and effective machines and techniques appear on the horizon. Now, forms of heavy-ion radiation alpha particles, neutrons, pi mesons, protons and other subatomic particles can be aimed at several kinds of tumors and can achieve high cure rates. These exotic forms of radiation are being explored in university medical centers, often in collaboration with physics departments, using their subatomic particle accelerators.
Drugs and chemicals that sensitize cancer cells to the destructive effects of radiation, thereby making it possible to destroy the cancer cells at lower doses, are also being developed. Still another experimental technique involves the use of hyperthermia higher than normal body temperature that can be induced by computer-directed microwave radiation. By using this complicated-sounding but relatively simple method of raising the temperature of a particular part of the body, the cancer cells can be made even more vulnerable to radiation.
Cancer cells that are subjected to higher-than-normal temperature are particularly sensitive to damage from radiation, possibly because of the compound effects of altered metabolism, radiation damage, and changes caused by the heat itself. Furthermore, the cancer cells deep inside a tumor do not have as much oxygen as those located nearer the surface. It seems that these oxygen-poor cells are more sensitive to heat than those that have a more oxygen-rich environment. Again, the effect is to make the combination of heat and radiation even more effective in reaching the core cancer cells.