Postoperative Radiotherapy for Patients with Stage II or III Nonsmall Cell Lung Cancer treated with Sublobar Resections: A SEER Registry Analysis Scott Edelman *, M.D., Robert H. Riffenburgh, PhD +, Walter J. Curran M.D* * Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA and Department of Radiation Oncology, Atlanta VA Medical Center, Atlanta, GA + Clinical Investigation Department, Naval Medical Center San Diego, San Diego, CA, and Department of Mathematics and Statistics, San Diego State University, San Diego, CA

 Patients who received PORT were younger than patients who did not receive PORT.  Large primary, more advanced nodal disease, and surgical procedure more limited than a wedge resection (e.g., fulguration, laser ablation) were associated with PORT  Bronchioloalveolar histology was a predictor for no PORT.  In summary, unfavorable tumor prognostic factors were associated with PORT administration, a selection bias favoring absence of PORT. Younger patients were more likely to receive PORT, a selection bias favoring PORT.

 For patients with stage II and III NSCLC, PORT was associated with inferior survival compared to no PORT. However, on multivariate analysis, PORT was not significantly, independently associated with inferior survival.  In contrast to SEER data for RT after lobectomy or pneumonectomy, for N2 patients who had sublobar resection, PORT was not associated with improved survival.  For tumors greater than 5 cm, PORT was associated with improved survival compared to PORT, with 5 yr OS of 15% and 0 respectively, (p=0.011). However, on multivariate analysis, PORT was not independently associated with improved survival for this subgroup.

 Our data do not provide any information on the role of PORT for patients with positive surgical margins, or for patients whose operating surgeon strongly feels that their resection was not adequate.  The lobectomy data in favor of PORT cannot be extrapolated to support the use of PORT for N2 disease for patients with stage II or III NSCLC treated with sublobar resection, and there is no outcome data to support such treatment for these patients.  Although patients with sublobar resections may be more at risk than lobectomy patients for local residual disease, this study did not demonstrate a survival benefit of PORT for patients with stage II or III NSCLC treated with sublobar resection.  PORT may possibly offer a survival for patients treated with sublobar resections for NSCLC, stage II and III, and primary tumors >5cm.