Precision medicine research out of Cleveland Clinic shows that genetic testing can be used to adjust cancer radiation therapies to the benefit of patients.
Radiation treatments for cancer provided by hospitals and oncology groups may be safer and more effective when the dose of radiation is tailored to each patient’s genetic risk factors. By providing genomic-adjusted radiation dosing, hospital leaders could potentially decrease the risk of expensive complications and improve the quality of their oncology services.
Research recently published in The Lancet Oncology examined the relationship between 10 genes thought to affect patients’ sensitivity to radiation and risks and benefits that different doses of radiation provide. This study included over 1,600 patients and was conducted by a team of researchers from Cleveland Clinic, the Moffitt Cancer Center in Tampa, and Case Western Reserve University in Cleveland.
Called genomic-adjusted radiation dosing, or GARD, this method of providing radiation therapy differs from traditionally used techniques. Typically, the dose of radiation used to treat tumors may be individualized to the size and type of a patient’s cancer, but it does not currently take the patient’s unique physiological makeup into consideration.
Lead study author Jacob G. Scott, MD, DPhil, is an associate professor at Case Western Reserve University School of Medicine and radiation oncologist at Cleveland Clinic. “As opposed to physical radiotherapy dose, which is the measure of what comes out of the machine and is delivered to the patient, GARD quantifies the biological effect on an individual patient of that delivered dose,” said Scott in a Cleveland Clinic news release.
“What we’ve found by looking at 1,600-plus patients is that the physical dose of radiation does not associate with outcome (time to first recurrence and overall survival), but GARD does,” he added.
GARD Approach Reduces Risks of Radiation Treatment
Radiotherapy does carry inherent risks, as radiation can potentially damage healthy tissues and increase a patient’s likelihood of experiencing complications. Providing GARD increases the overall survival rates of patients who receive this form of therapy when compared to traditional radiation treatments, while simultaneously reducing the risks associated with treatment, researchers found.
This multi-institutional research initiative also questions some of the fundamental assumptions of radiation therapy science.
“Historically, the field of radiotherapy has accepted that radiation therapy, a physical treatment, causes a biologic or clinical effect in patients with regard to tumor response, toxicity, and carcinogenesis,” said senior study author Javier Torres-Roca, MD, senior member in the Department of Radiation Oncology at Moffitt Cancer Center and professor of oncologic sciences at the University of South Florida Morsani College of Medicine.
“However, up to now, radiation oncologists have always assumed that the biological effect was uniform across patients,” Torres-Roca continued. “GARD provides the first validated approach to quantify the biological effect of radiotherapy for each individual patient and tells you more about the clinical outcome and the benefit of radiotherapy than the physical dose.”
Added Tool for Cancer Treatment
While GARD would be a new approach to cancer radiation therapy, it could integrate well into the current treatment methodologies, Scott argued.
“This does not require a departure from the current standard of care,” he said. “Our view is that radiosensitivity index/GARD is a decision support tool that provides a view of the effect of radiotherapy dose for each individual patient, providing critical information for the treating radiation oncologists.”
Radiation oncology was highlighted as a potential field that would benefit from precision medicine in a 2016 paper published in Nature Reviews Cancer; however, this focus was limited to developing biomarkers and bio-imaging. Previous work in this field has helped to provide more information about how to locate and identify tumors, but it has not resulted in personalization of the actual treatment provided.
“Radiation oncology is lagging behind medical oncology in having genomic tests that help us understand both who should receive radiation and how much radiation they should get,” said Wendy Woodward, MD, PhD, a radiation oncologist at the University of Texas MD Anderson Cancer Center in an interview with The Scientist. “What is unique about GARD, if it turns out to be clinically validated, is that it’s the only one of these tests that’s really trying to give us information about what dose we should be giving people.”
Woodward was not involved in the research, but has previously collaborated with the authors.
While GARD still requires clinical validation before it can be routinely used in a clinical setting, it represents a potential advance in precision medicine in oncology that hospitals can bring into clinical practice. Hospital leaders and oncology directors should follow the developments in this area and be prepared to modify existing radiation therapies to offer genomic-based dose adjustments. This change could decrease the expense of hospital-acquired complications while improving clinical outcomes.