Radiation therapy is the most overlooked of cancer therapies. While attention has primarily been given to chemotherapy and immunotherapy, the truth is that for every 100 people who survive cancer, about 50 can principally thank surgery, 45 are alive because of radiation therapy and perhaps 5 survive due to all other therapies. As cancer death rates continue to decline, we must recognize and support the critical role that radiation therapy plays in this trend.
Of the $2.2 trillion spent by the U.S. economy on healthcare, less than one percent (about $800 million) is spent on radiation therapy equipment—this, despite the fact that radiation therapy serves as our safest, most convenient and cost-effective method of treating cancer.
Consider this: Unlike surgery, most people receiving radiation therapy are not hospitalized. Most patients who undergo radiation therapy experience minimal side effects, and the incidence of complications is dropping rapidly as survival rates continue to improve. Modern radiation therapy solutions are an important part of this progress. Recently published results1 of an ongoing clinical trial for the treatment of lung cancer—the most deadly of all cancers—illustrates this very fact.
Encouraging early results
The Phase I clinical trial, led by the University of Wisconsin School of Medicine and Public Health, shows that using TomoTherapy technology to safely deliver a higher-than-normal biologically-effective dose to stage I-IV non-small cell lung cancer patients results in increased overall survival, and reduced rates of toxicity to lung and esophagus. A key area where the treatment technique differed from traditional radiotherapy is that all patients received just 25 treatment fractions and the dose per fraction was set according to the likelihood of radiation-avoiding lung pneumonitis and esophagitis. Some patients were able to receive a higher dose per fraction than others (mostly because their tumor was smaller), taking advantage of the increase in survival known to be associated with increased tumor dose. Unlike most dose escalation studies, increased dose was not achieved by increasing the total number of fractions (and total duration of the treatment course), as this can allow time for the tumor to begin re-growing.
Highlights of the study
The authors state that “higher doses of radiation therapy than are conventionally administered (~60 Gy) may be delivered safely in a hypofractionated schedule with helical TomoTherapy.”
For the 46 patients in the study, overall survival 2 years after treatment was 46.8%. This compares with historical rates of only 21.5% for the same stage-range of disease.
No patient experienced grade 3 or higher pneumonitis and no patient experienced grade 3 or higher esophagitis. It is important to note that this study does not employ a stereotactic body radiotherapy (SBRT) technique, which benefits a much smaller number of patients (mostly very small, Stage I tumors). The majority of patients in this study had Stage III or IV lung cancer, as do about 60% of lung cancer patients at diagnosis.
Radiation therapy as a wonder drug
Everyone hopes for a wonder drug like penicillin or a vaccine to cure cancer. Imagine for a moment that radiation therapy were a drug. It could be administered in dosages accurate to within a few percent. It could be instantly detected in the smallest quantities. The tumor would not build up tolerance to it. It would be inexpensive to deliver. And it would accentuate the tumorcidal effects of other drugs.
Now imagine that where the drug acts were visible with medical imaging, and that it could be delivered anywhere in the body with minimal side effects. Surely, it would be heralded as the wonder drug of our age.
Radiotherapy is that wonder drug—for certain cancers. This type of therapy is able to treat those hard-to-treat cancer cases. Advances in computer and radiation technology have made it possible to create new radiation delivery systems that target the tumor and spare surrounding healthy tissue. For example, it is now possible to accurately treat cancers where the tumor is very near to a critical organ like the spinal cord. The company that I co-founded in Madison, Wisconsin, TomoTherapy Incorporated, has developed such a device that is being used throughout the country and world.
Incorporating CT scanning technology, the TomoTherapy Hi·Art treatment system is able to visualize and treat deep-seated tumors that are larger than any ever even attempted, and achieve unprecedented avoidance of surrounding normal tissues.
Much has been written about why the cancer death rate is dropping. Better screening, earlier detection and improved lifestyles have been reported on extensively by the media. This is justified and serves a good purpose. But let us also raise awareness of an improved application of a weapon that has long been an essential component in our battle against cancer, radiation therapy. As a nation, we need to continue supporting these efforts because they do work and, with the proper research and development put into them, they will continue to improve—and prove ever-more effective in the fight against cancer.
Thomas Rockwell Mackie, Ph.D.
Dr. Mackie is a professor at the University of Wisconsin and co-founder and Chairman of the Board of TomoTherapy Incorporated.1 “Dose Escalated, Hypofractionated Radiotherapy Using Helical Tomotherapy for Inoperable Non-Small Cell Lung Cancer: Preliminary Results of a Risk-Stratified Phase I Dose Escalation Study,” Technology in Cancer Research and Treatment (Technol Cancer Res Treat. 2008 Dec;7(6):441-8.)