Addressing the variation in hepatic surgery for colorectal liver metastasis

Liver surgery for colorectal liver metastasis (CRLM) has evolved considerably over the past two decades. Novel chemotherapy regimens and effective targeted therapy, changes in the view of resectability criteria and evolution of safer surgical principles have led to increasing resection rates and better overall survival for an increasing number of patients with stage IV colorectal cancer (1). While the survival benefit from resection CRLM is welldocumented and long reported in the medical literature, there continues to be a disturbing variation in the access and provision of liver surgery across population-based studies. Indeed, variation in the delivery of surgical services is welldescribed in general, but many aspects of its causes a poorly understood. Variation in the provision and outcomes of liver surgery has been demonstrated in several nationwide studies from Germany (2), Sweden (3), and Norway (4). A UK-based study in the early 2000s (5), demonstrated a low resection rate for CRLM. In the period from 1998 to 2004, the hepatectomy rate in the UK increased from 1.7% to 3.8%, suggesting an underutilization of liver surgery as such in the population. A <4% resection rate was arguably well below the >10% reported from the MD Anderson during the same period (1) and far below that rate levelling off at about 20%. Notably, the increase in resection rate came with the introduction of novel and more effective chemotherapy regimens, pointing to the importance of multidisciplinary evaluation and management to optimize treatment strategy for improved outcomes. Obviously, resection rates in a single-institution referral centre cannot be used as reference for a populationbased study. However, in a population-based study from Norway, a resection rate at around 20% was demonstrated with negligible variation between regions (4). Thus, when revisiting UK data in the largest population-based study to date (6), it is concerning to see the resection rate reported at 4.1% in 2005 only increase to and plateauing at around 5% in 2012. The very slow take-up on liver surgery (5,6) and potential 4-fold lower resection rate in UK (about 5%) (6), compared to institutional and contemporary populationbased rates (1,4) (about 20%) is concerning. Causes to this variation needs to be explored.