Is there a role for consolidative stereotactic body radiation therapy following first-line systemic therapy for metastatic lung cancer? A patterns-of-failure analysis

Introduction. The pattern of failure (POF) after first-line systemic therapy in advanced non-small cell lung cancer (NSCLC) is unknown. We evaluate the POF in this setting to estimate the potential value of consolidative stereotactic body radiation therapy (SBRT). Materials and methods. The records of consecutive NSCLC patients presenting to the University of Colorado, Denver (UCD) between January 2005 and June 2008 were reviewed. Patients with measurable advanced stage NSCLC who received first-line systemic therapy and follow-up at UCD were eligible. In these patients, sites of disease at maximal response were evaluated for theoretical SBRT eligibility, based on institutional criteria. All patients were followed to extracranial progression. The POF was categorized as local (L) for lesions known prior to treatment or distant (D) for new lesions. Results. Among 387 consecutive lung cancer patients (all stages), 64 met the eligibility criteria and 34 were SBRT-eligible. Among all eligible patients, first extra-cranial progression was L-only in 64%, D-only in 9% and L + D in 27%. Among SBRT-eligible patients, POF was L-only in 68%, D-only in 14% and L + D in 18%. In SBRT-eligible patients, time to first progression was 3.0 months in those with L-only failure versus 5.7 month in those with any D failure (HR 0.44; 95% CI 0.22–0.90). Conclusions. The predominant POF in patients with advanced NSCLC after first-line systemic therapy is local-only. The current analysis suggests that SBRT could improve time to progression in a substantial proportion of patients. The estimated increase in time to progression using this approach would be approximately 3 months.