Michigan Medicine, in a recent collaboration with other medical centers, conducted a study to test whether computer-optimized radiation therapy reduced skin irritation and pain in breast cancer patients and improved the effectiveness of the treatment.
The treatment is called reverse planning and intensity modulation radiation therapy. It has been found to reduce these side effects more effectively than three-dimensional conformational radiation therapy (3D CRT), which is commonly used to treat many types of cancer, including breast cancer.
3D CRT treats cancer by sending radiation from multiple angles with the goal of protecting healthy tissue but attacking tumors, or conforming to the tumor, according to the University of Alabama School of Medicine. The Michigan Radiation Oncology Quality Consortium, the organization that initiated the study, reported that the use of reverse planning IMRT rather than 3D CRT significantly decreases the acute toxicity of radiation therapy to the breast.
Reshma Jagsi is vice president of radiation oncology and director of the Center for Bioethics and Social Sciences in Medicine at Michigan Medicine. Jagsi was also a lead author of the study and explained that reverse planning IMRT is beneficial because instead of treating tissue through a single beam of uniform intensity, this treatment changes the uniformity. of a beam of radiation.
“If I process that half for a while, then block it, and keep processing that (other) half for more, half of the field has become more intense than the other,” Jagsi said. “You can do it roughly and just snap (the beam) in half. You can divide it into shapes, segments, and you can even vary the intensity pixel by pixel. And that requires computerized treatment planning and optimization.
Reverse planning IMRT works by using specialized computers to calculate the radiation dose needed for specific parts of a tumor. According to the National Library of Medicine, the computer calculates a “figure of merit” or “the ratio of the delivered tumor dose to the normal tissue dose”, to ensure maximum effectiveness of radiation therapy.
Radiation oncologist Frank Vicini helped analyze the data and co-authored the study manuscript. He said the study was important because it showed, for one of the first times, the effect of IMRT compared to 3D patients.
“I think the uniqueness of this is that it is one of the largest, if not the largest database now, documenting that patients treated with reverse planning IMRT have done, not much better, but better than 3D patients, ”said Vicini. . “Patients treated even with 3D have done very well, but it shows that reverse planning IMRT, the most sophisticated technique, has resulted in a 5-10% reduction in the acute toxicity experienced by patients.”
As Vicini said, this study was one of the largest of its kind, comparing data from 23 institutions from 2011 to 2018.
Vicini noted that there are still questions to consider as reverse-planning IMRT develops, such as whether the additional economic cost of using reverse-planning IMRT is achievable for patients and whether patients can still use 3D CRT processing with more efficient methods.
“There is no doubt that the patients (using reverse planning IMRT) did better, but is this something that can only be achieved with IMRT? Said Vicini. “Or, by learning what really happened… can we actually do the same with 3D (processing)? ”
Many researchers continue to study reverse planning IMRT. Asked about her motivation to participate in the study, Jagsi said it was important to consider the side effects of the treatment on patients.
“One of the benefits of treating breast cancer these days is that we are often able to cure the disease and have long-term survivors,” Jagsi said. “And that makes us especially mindful of the side effects of our treatments and how we can make sure that the treatments we give are tolerable for our patients so that they can get the full treatment and not be in pain, and continue to do so. live the long, healthy and productive lives with the high quality of life we want for them.
Daily journalist Rachel Mintz can be contacted at [email protected]