A liquid biopsy that measures circulating lung tumor DNA at the end of treatment identifies patients with early non-small cell lung cancer (NSCLC) with a poor prognosis, according to research presented at the American Society for Radiation Oncology (ASTRO) annual meeting (September 24-27, 2017; San Diego, CA).
In hematology, minimal residual disease is considered a prognostic biomarker of treatment efficacy. Circulating tumor DNA has the potential to detect minimal residual disease after definitive treatment for NSCLC and could be prognostic for disease progression and survival.
Aadel Chauduri, MD, PhD, Stanford Cancer Institute, and colleagues conducted a small study to test this potential. A total of 41 patients were enrolled with localized NSCLC (stage IA-IIIB) who were treated definitively with radiotherapy or surgery, with or without chemotherapy. Minimal residual disease was assessed by circulating tumor DNA analysis within 4 months of treatment completion.
Results of the analysis showed that patients with detectable circulating tumor DNA (minimal residual disease-positive) at the post-treatment evaluation had significantly inferior freedom from disease progression compared with those who had minimal residual disease-negative status (HR, 41.3; P < .00001). Similar inferior results were documented for disease-specific survival and overall survival. Measurement of circulating tumor DNA identified disease recurrence 5.5 months earlier than follow-up chest CT imaging.
Additionally, researchers reported that cancer returned within 2 years in all of the patients who had detectable circulating tumor DNA, whereas only one patient with undetectable circulating tumor DNA had a recurrence.
End-of-treatment minimal residual assessment may provide clues to potential therapies that might improve outcomes for patients with detectable circulating tumor DNA, Dr Chauduri explained. Results showed EGFR mutations in over 50% of the patients in the study, whereas the remaining patients might have benefited from chemotherapy or immunotherapy.
“We found that circulating tumor DNA minimal residual disease detection after treatment correlated significantly with worse progression-free and overall survival,” Dr Chauduri said. “These findings suggest that circulating tumor DNA minimal residual disease may be useful for selecting patients for early administration of targeted therapies.”—Zachary Bessette