title: Does early posttreatment surveillance imaging affect subsequent management following stereotactic body radiation therapy for early-stage non-small cell lung cancer?
abstract: OBJECTIVE
  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
  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.
authors.affiliation: Department of Radiation Oncology, University of California Davis, Comprehensive Cancer Center, Sacramento, California. Electronic address: megan.daly@ucdmc.ucdavis.edu.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Daly
authors.affiliation: Department of Biostatistics, University of California Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Beckett
authors.affiliation: Department of Radiation Oncology, University of California Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: Allen M
authors.initials: AM
authors.lastname: Chen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D019468:Disease Management; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D049268:Positron-Emission Tomography; D016634:Radiosurgery; D061665:Time-to-Treatment; D014057:Tomography, X-Ray Computed