Does institutional patient accrual volume impact overall survival in patients with inoperable non-small-cell lung cancer receiving radical (chemo)radiation? A secondary analysis of TROG 99.05.

INTRODUCTION: Increased hospital patient volume, reflecting greater experience, has been shown to be associated with improved survival for some cancers. However, there is no evidence to support the volume-outcome hypothesis for inoperable non-small-cell lung cancer (NSCLC) patients within the Australasian setting. We examined the relationship between overall survival (OS) and institutional patient accrual volume (IPAV) in a large prospective Australasian NSCLC database (TROG 99.05). METHODS: TROG 99.05 was an observational study which accrued patients from 1999 to 2007 to examine the relationship between primary lung cancer volume and survival. To be eligible for inclusion, patients had to have inoperable, biopsy-proven NSCLC planned for radiotherapy to a minimum dose of 50Gy in 20 fractions, with or without chemotherapy. Participating institutions were de-identified and grouped according to whether accrual was low, medium or high. OS was compared between groups and adjusted for prognostic factors using Cox regression. RESULTS: About 509 patients were accrued from 16 centres. Median potential follow-up time was 60 months. Median survival for all groups was 20 months (95% CI 18.3-21.8 months). There were no statistically significant differences in OS with increasing patient accrual across the three groups after adjustment for prognostic factors (P = 0.84, 2 df). The hazard ratios (HR) for group accrual volumes, relative to that for high-accrual volume, were as follows: low, 1.18; medium, 1.14. Test for trend: HR = 0.91 per group (95% CI 0.76-1.09, P = 0.31). CONCLUSION: In the setting of a clinical trial with rigorous quality assurance, we found no evidence for an association between institutional accrual and survival.