Purpose: Uncertainty exists regarding the optimal surveillance imaging strategy following stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (NSCLC), particularly with respect to timing. We sought to determine how routine use of early (<6 months) posttreatment imaging affects subsequent management.
Methods and materials: The records of all patients treated with SBRT between January 2007 and January 2013 for early-stage NSCLC were reviewed. Eligible patients underwent ≥ 1 early (defined as within 6 months following SBRT) surveillance imaging study. Radiographic findings and subsequent diagnostic or therapeutic interventions were identified. Proportions and exact 95% confidence intervals (CI) with early posttreatment surveillance findings and altered treatment were calculated, and cases were examined descriptively.
Results: Sixty-two patients with 67 lung tumors underwent 92 early surveillance imaging studies (86 computed tomographic [CT] and 6 positron emission/CT) at a median of 2.1 months (range, 0.1-5.9 months). New lung nodules were identified in 8 patients (13%), leading to a diagnosis of metastatic disease treated with systemic therapy in 2 patients and biopsy proven solitary lung recurrence in 2 patients, both treated successfully with local therapy. Tumor growth meeting Response Evaluation Criteria in Solid Tumors (RECIST) criteria was identified in 1 patient, who was followed with subsequent radiographic regression. In aggregate, the treatment of 4 patients (6.5%, 95% CI 1.7%-15.2%) was altered by early imaging; 2 (3.2%, 95% CI 0.4%-10.8%) with a potentially curative intervention. No predictors for utility of early surveillance were identified.
Conclusions: Imaging within 6 months following SBRT for early-stage NSCLC resulted in a definitive intervention in approximately 3% of patients. In the era of cost-effective health care, a first scan at 6 months posttreatment may be adequate for most patients. Larger scale prospective studies are needed to address the optimal surveillance regimen following SBRT and to identify patients who may benefit from more aggressive surveillance regimens.
© 2014.