Postoperative Radiation Therapy Improves Overall Survival for Patients With Resected Pathologic N2 Non–Small Cell Lung Cancer
Patients who received postoperative radiation therapy lived an average of 4 months longer when compared to the patients who had the same disease site, tumor histology, and treatment criteria and who did not receive postoperative radiotherapy, according to research presented at the 2014 Chicago Multidisciplinary Symposium in Thoracic Oncology (Abstract 128).
This study reviewed the records of non–small cell lung cancer (NSCLC) patients treated from 2004 to 2006 from the National Cancer Data Base, a joint endeavour of the Commission on Cancer of the American College of Surgeons and the American Cancer Society. The study authors acquired the data for patients who had surgically resected NSCLC with pathologically involved N2 lymph nodes and who received chemotherapy.
The database was further queried to exclude patients with positive margins, incomplete survival data, those who did not receive adjuvant chemotherapy, histology other than NSCLC, and patients treated with cobalt-60, nonbeam radiotherapy or neoadjuvant radiotherapy. A total of 2,115 patients met all of the study criteria. About 43% (n = 918) received postoperative radiotherapy, and 56.6% (n = 1,197) were not treated with postoperative radiotherapy.
Key Findings
Factors associated with overall survival were assessed through a multivariable Cox proportional hazards model. Inverse probability of treatment weighting using the propensity score was also implemented to reduce biased treatment selection. Using an adjusted Kaplan-Meier estimator and the weighted log-rank test, patients treated with postoperative radiotherapy had an improved median overall survival of 42 months compared to 38 months for the patients not treated with postoperative radiotherapy (P = .048).
Multivariable analysis revealed that female gender, adenocarcinoma histology, higher income, urban/rural setting vs metropolitan setting, lower T stage, one to two involved lymph nodes vs at least three examined and involved lymph nodes, and younger age correlated with better overall survival (P < .05). No direct relation was found between the effects of postoperative radiotherapy and the number of involved lymph nodes.
Implications for Practice
“These results reinforce the value of [postoperative radiotherapy] for non–small cell lung cancer patients with involved mediastinal lymph nodes. Our data indicate that with modern radiotherapy equipment and treatment techniques, [postoperative radiotherapy] can improve survival for these patients,” said John L. Mikell, MD, lead study author and Chief Resident in the Department of Radiation Oncology at Emory University Winship Cancer Institute in Atlanta.
“The data in this study, the largest, most recent cohort of patients with involved mediastinal nodes treated with chemotherapy, reinforce that [postoperative radiotherapy] should be considered in addition to chemotherapy following resection of non–small cell lung cancer,” he said.
The Symposium is sponsored by the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), the International Association for the Study of Lung Cancer (IASLC) and The University of Chicago Medicine.
The study authors reported no potential conflicts of interest.
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