Refining Surveillance Guidelines after Stereotactic Body Radiation Therapy for Early-Stage Lung Cancer

Introduction: Stereotactic body radiation therapy (SBRT) is a treatment for patients with early-stage non-small cell lung cancer (ES-NSCLC). Surveillance guidelines vary after treatment. While patients are more likely to locally recur within 2 years of treatment, there remains a paucity of data on the benefit of frequent and long-term surveillance. We evaluated a cohort of NSCLC patients to evaluate surveillance patterns and outcomes. Materials and methods: Patients with ES-NSCLC treated with SBRT were retrospectively evaluated. Imaging was reviewed after SBRT for evidence of recurrence or new malignancy. The median scan interval (MSI) was calculated as the median number of months between surveillance scans. The MSI between patients with or without new disease was compared by t-test. New disease development and survival between patients with <T2 or >=T2 disease and with or without prior malignancy was compared using χ², Kaplan-Meier analysis, and Gray's test. Results: A cohort of 168 patients with median follow up of 23.4 months met criteria for review with 50% developing new disease. MSI did not differ between patients with or without new disease. Patients with >=cT2 tumors had worse overall survival and trended towards higher incidence of new disease. New disease continued to occur, even 5 years after treatment. Conclusion: Increased scan frequency did not increase detection of new disease. Patients continued to fail 5 years after treatment. Larger tumors trended toward more frequent failures and those patients experienced worse OS. Surveillance guidelines should be optimized to prevent over surveillance after treatment and to continue long-term surveillance.