Nov. 3, 1999 Mixing neutrons and photons as the types of radiation used to treat cancer confined to the prostate results in a 90 percent three-year disease free survival rate, a new study shows.
The results of the study, conducted at Wayne State University in Detroit, MI, were presented November 1 at the American Society for Therapeutic Radiology and Oncology annual meeting in San Antonio, TX.
The study of 300 patients found that patients who were treated with neutrons first followed by photons had the best results, says Jeffrey Forman, M.D., interim chair of the department of radiation oncology at Karmanos Cancer Institute in Detroit. "Ninety-five percent of patients who received neutrons first were free of cancer recurrence at four years compared to 73 percent who were treated with photons first," he says. "The improved outcome could mean that the neutron radiation therapy is sensitizing the cancer cells so they can be killed by the photon irradiation," theorizes Dr. Forman.
Combining neutron and photon therapy did not increase the side effects, notes Dr. Forman. The level of side effects was comparable to standard treatment for this disease, he adds.
Photon radiation is the type of radiation that is commonly used in external beam radiation therapy. On the other hand, neutron therapy is available in only a few centers because it requires extensive technology - a cyclotron, Dr. Forman says.
"We will follow these patients closely to confirm whether improvement in disease free survival translates into improvement in overall survival. Because of the limited number of neutron facilities it will be interesting in the future to compare this technique with high dose conformal radiation therapy. Still, the results seen in this group that received neutrons first and then photon radiation were remarkable, says Dr. Forman.
The American Society for Therapeutic Radiology and Oncology (ASTRO) is the largest radiation oncology society in the world, with more than 5,000 members. As a leading organization in radiation oncology, biology and physics, the society's goals are to advance the scientific base of radiation therapy and to extend the benefits of radiation therapy to those with cancer.
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