Doctors may someday be able to advise cancer patients to skip potentially grueling radiation therapy that won’t work on their specific tumors, a new study suggests.
The findings, which appear in Cancer Research, could potentially lead to a non-invasive method for identifying patients are who ill-suited for radiation treatment, which would reduce medical overtreatment and help patients avoid adverse effects of radiation.
“Our eventual hope is to be able to predict a patient’s response before radiation therapy even begins, thus sparing patients whose tumors can’t be treated with radiation from going through the arduous multi-week process, saving them both time and money,” says Ishan Barman, assistant professor of mechanical engineering at Johns Hopkins University and one of the study’s corresponding authors.
Typical radiation therapy delivers small doses of radiation over a period of five to seven weeks. There is currently no definitive way to predict treatment response before or even in the early weeks of therapy. The earliest clinicians can examine tumor shrinkage is two to three weeks after therapy, using CT and MRI scans.
Side effects of radiation treatment differ depending on the cancer involved, but can include fatigue, hair loss, nausea, diarrhea, swallowing issues, shortness of breath, and fertility problems, among others, the National Cancer Institute says.
Radiation in small doses
While other studies have investigated molecular changes in tumors as a way to preemptively identify tumors that will not respond to radiation treatment, Barman’s team says its study is unique.
Team members studied multiple types of cancers and used smaller doses of radiation, which more accurately reflects current radiation therapy practices.
“Previous researchers used a single large dose of radiation, resulting in biomolecular changes that don’t accurately mimic the subtle changes caused by smaller doses delivered over longer periods of time,” says first author Santosh Paidi, a mechanical engineering graduate research assistant.
Researchers used Raman spectroscopy, employing laser light to examine how molecules vibrate. Using that method, they were able to characterize changes in the biochemical composition of a tumor and its environment. This method, the researchers say, requires only a low-power laser and doesn’t need any additional sample preparation; such technologies enable holistic examination of the complex biological process of radiation treatment.
“This is only the first step of a larger research endeavor to determine how head and neck cancer tumors respond to radiation.”
To test the difference in response from tumors that are sensitive to radiation and those that are resistant, the researchers used cell lines of both resistant and sensitive tumors from human lung cancers as well as head and neck cancers to grow tumors in mice.
After the tumors grew to a certain size, the research team removed them and scanned them with a Raman spectroscopy system. All four tumor types showed changes in response to small doses, meant to replicate clinical radiation therapy practice in humans, given over the course of two weeks.
The researchers also found consistent changes in lipid and collagen content in both lung, and head and neck tumors.
Ultimate goal
For the second part of the experiment, the research team examined untreated lung tumors. Raman spectroscopy provided data that allowed the research team to distinguish between radiation-resistant and radiation-sensitive tumors, thus providing key insight into the roles different molecules may play in making tumors resistant to radiation.
The research team found subtle differences in each tumor type’s spectrographic signature. After analyzing these patterns, the researchers created an algorithm that identified radiation resistance and sensitivity with a 97 percent success rate.
“This is only the first step of a larger research endeavor to determine how head and neck cancer tumors respond to radiation,” Barman says.
“The ultimate goal is to build a miniature probe that can fit into a laryngoscope. Hopefully in the future, then, when a clinician performs an endoscopy and looks at a patient’s cancerous tumor, they’ll be able to determine whether that tumor will even respond to radiation therapy, and that can improve treatment plans.”
Additional researchers are from Johns Hopkins, the University of Arkansas, and the University of Arkansas for Medical Sciences. The National Institutes of Health, Johns Hopkins, the Arkansas Biosciences Institute, the Medical Research Endowment Fund, the Winthrop P. Rockefeller Cancer Institute, and the Center for Microbial Pathogenesis and Host Inflammatory Responses funded the work.
Source: Johns Hopkins University
