Survival following sublobar resection for early-stage non-small cell lung cancer with or without adjuvant external beam radiation therapy: a population-based study.

BACKGROUND: Patients undergoing sublobar resection for early-stage non-small cell lung cancer may receive adjuvant radiation therapy in an effort to improve outcomes despite limited data regarding its efficacy.
METHODS: Using the Surveillance, Epidemiology, and End-Results (SEER) registry we identified patients diagnosed with stage I non-small cell lung cancer between 1988 and 2003 who were definitively treated with sublobar surgical resection with or without adjuvant external beam radiation therapy. Kaplan-Meier, Cox regression, and propensity-score-matched survival analyses were performed to evaluate the effect of adjuvant external beam radiation therapy on survival.
RESULTS: A total of 5,908 eligible cases were identified: 493 received external beam radiation therapy and 5,415 received no additional local-regional treatment. The use of external beam radiation therapy was associated with significantly worse median overall and disease-specific survival compared with no additional local-regional therapy: 31 and 45 months vs 51 and 98 months, respectively (P < .001). On multivariate analysis, the most significant predictor of death was the use of adjuvant radiation therapy (hazard ratio 1.505; 95% CI, 1.318-1.717; P < .001). The survival detriment associated with external beam radiation therapy remained after propensity-score-matched analysis.
CONCLUSIONS: The use of adjuvant external beam radiation therapy is associated with a significant decrease in overall and disease-specific survival for patients with T1-2N0M0 non-small cell lung cancer treated with sublobar resection. Although this finding may be related to covariables not reported in SEER, such as margin status, chemotherapy use, radiation dose, and portal, alternative radiation treatment strategies should be explored.