Stereotactic body radiation therapy dramatically prolonged progression-free survival and overall survival in a phase II study of 24 patients who had limited but progressive metastatic non–small-cell lung cancer.
The findings were published online Oct. 27 in Journal of Clinical Oncology.
When added to erlotinib, the aggressive local radiation technique, which delivers high doses in a few treatment sessions to extracranial malignant deposits, more than doubled progression-free and overall survival, compared with that in historical control subjects. These findings “encourage consideration of a new treatment paradigm with the inclusion of aggressive noninvasive local therapy in the form of stereotactic body radiation therapy,” said Dr. Puneeth Iyengar, a radiation oncologist at the University of Texas Southwestern Medical Center, Dallas, and his associates.
The study participants were adults with stage IV NSCLC who had undergone at least one systemic chemotherapy regimen and still had up to six metastases, most often in the lung parenchyma, mediastinal or hilar nodes, adrenal glands, liver, and spine. The contours of 52 metastatic deposits were mapped and treated with stereotactic body radiation therapy (SBRT). All the patients also received erlotinib, beginning 1 week before radiotherapy began and continuing until disease progressed or patients opted to stop the drug.
The primary efficacy outcome, median 6-month progression-free survival, was 69%. After a mean follow-up of 17 months (range, 3-60 months), median progression-free survival was 14.7 months and median overall survival was 20.4 months. In comparison, progression-free survival was only 2-4 months and overall survival only 6-9 months in historical cohorts of patients with stage IV NSCLC who progressed through multiple rounds of cytotoxic chemotherapy but did not receive SBRT.
At 3-month follow-up, 10 of 47 evaluable lesions were no longer visible and 24 others showed a reduction in volume of at least 30%. None of the metastases treated with SBRT showed any progression for at least 9 months.
“Our approach dramatically changed the pattern of relapse, with a shift in failure from existing sites (i.e., local) to new sites (i.e., distant). One-third of patients were able to receive additional cytotoxic chemotherapy after progression on our trial, with SBRT potentially allowing this subset to tolerate subsequent agents by delaying continued use,” Dr. Iyengar and his associates wrote (J. Clin. Oncol. 2014 Oct. 27 [doi:10.1200/JCO.2014.56.7412]).