Association between hospital volume and mortality of patients with metastatic non-small cell lung cancer

Background: Prior studies have shown superior surgical outcomes of stage non-small cell lung cancer (NSCLC) in centers with higher patient volumes. However, there is a lack of such information in stage IV NSCLC. Patients and methods: This is a retrospective study of stage IV NSCLC patients diagnosed between 2004 and 2014 using the National Cancer Data Base (NCDB). We classified the total number of patients treated at facilities into quartiles: quartile 1 (Q1): <= 23; quartile 2 (Q2): 24-36, quartile 3 (Q3): 37-55, and quartile 4 (Q4): >= 56 cases/year. Cox regression was used to assess whether risk of death differed between quartiles after adjusting for demographics, insurance type, Charlson-Deyo score, and type of therapy received. Results: There were 338, 445 patients with stage IV NSCLC treated at 1326 facilities. We included the patients who received any form of therapy in the survival analysis. The unadjusted median overall survival by facility volume was: Q1: 6 months, Q2: 6 months, Q3: 7 months, and Q4: 8 months (p<.001). Multivariable analysis showed that facility volume was independent predictor of all-cause mortality. Compared with patients treated at Q4 facilities, patients treated at lower-quartile facilities had a small but significantly higher risk of death (Q3 hazard ratio [HR], 1.05 [95%CI, 1.04-1.06]; Q2 HR, 1.12 [95%CI, 1.11-1.14]; Q1 HR, 1.11 [95%CI, 1.10-1.12]). Conclusions: Patients who were treated for stage IV NSCLC at highest-volume facilities had less risk of all-cause mortality compared with those who were treated at lower-volume facilities. Although the survival advantage of being treated at highest-volume facilities appeared small, the results of this study suggest differences in cancer care delivery models among various facilities, and may become more relevant in the future era of personalized treatment of stage IV NSCLC.