The impact of provider surgical volumes on survival in children with primary tumors of the central nervous system—a population-based study

BACKGROUND: Provider volume is often a central topic in debates about centralization of procedures. In Norway, there is considerable variation in provider volumes of the neurosurgical centers treating children. We sought to explore long-term survival after surgery for central nervous system tumors in children in relation to regional provider volumes. METHOD: Based on data from the Norwegian Cancer Registry we analyzed survival in all reported central nervous system tumors in children under the age of 16 treated over two decades, between March 1988 and April 2008; a total of 816 patients with histologically confirmed disease. RESULTS: There was no overall difference in survival between regions. In the subgroup of PNET/medulloblastomas, both living in the high-provider volume health region and receiving treatment in the high-volume region was significantly associated with inferior survival. CONCLUSIONS: In this population-based study of children operated over a period of two decades, we found no evidence of improved long-term survival in the high-provider volume region. Surprisingly, a subgroup analysis indicated that survival in PNET/medulloblastomas was significantly better if living outside the most populated health region with the highest provider volumes. One should, however, be careful of interpreting this directly as a symptom of quality of care, as there may be unseen confounders. Our study demonstrates that provider case volume may serve as an axiom in debates about centralization of cancer surgery while perhaps much more reliable and valid but less quantifiable factors are important for the final results.