Post-operative radiation therapy for non-small cell lung cancer: A comparison of radiation therapy techniques

Objectives: Post-operative radiation therapy (PORT) in locally advanced non-small cell lung cancer (LA-NSCLC) has historically been associated with toxicity. Conformal techniques like intensity modulated radiation therapy (IMRT) have the potential to reduce acute and long-term toxicity from radiation therapy. Among patients receiving PORT for LA-NSCLC, we identified factors associated with receipt of IMRT and evaluated the association between IMRT and toxicity. Methods: We queried the Surveillance, Epidemiology, and End Results (SEER)-Medicare database between January 1, 2006 to December 31, 2014 to identify patients diagnosed with Stage II or III NSCLC and who received upfront surgery and subsequent PORT. Baseline differences between patients receiving 3-dimentional conformal radiation therapy (3D-CRT) and IMRT were assessed using the chi-squared test for proportions and the t-test for means. Multivariable logistic regression was used to identify predictors of receipt of IMRT and pulmonary, esophageal, and cardiac toxicity. Propensity-score matching was employed to reduce the effect of known confounders. Results: A total of 620 patients met the inclusion criteria, among whom 441 (71.2%) received 3D-CRT and 179 (28.8%) received IMRT. The mean age of the cohort was 73.9 years and 54.7% were male. The proportion of patients receiving IMRT increased from 6.2% in 2006 to 41.4% in 2014 (P < 0.001). IMRT was not associated with decreased pulmonary (OR 0.89; 95% CI, 0.62-1.29), esophageal (OR 1.09; 95% CI, 0.0.75-1.58), or cardiac toxicity (OR 1.02; 95% CI, 0.69-1.51). These findings held on propensity-score matching. Clinical risk factors including comorbidity and prior treatment history were associated with treatment toxicity. Conclusion: In a cohort of elderly patients, the use of IMRT in the setting of PORT for LA-NSCLC was not associated with a difference in toxicity compared to 3D-CRT. This finding suggests that outcomes from PORT may be independent of radiotherapy treatment technique.