Liver resection in the setting of obesity

An estimated 2.5 billion adults are classified as overweight or obese globally, a figure that has risen rapidly over the last number of decades (1). Deaths and disability related to high body mass index (BMI) have increased more than 2.5-fold since 1990, with the sharpest rise seen in low- and middle-income countries (2). A proportion of 3.6% of all new cancer cases, and 4.6% of all cancer deaths are attributable to high BMI globally (3). As a result of the obesity epidemic, and of the resultant metabolic syndrome, the prevalence of non-alcoholic fatty liver disease (NAFLD) is now 30% worldwide, with Latin America and Middle East-North Africa experiencing the highest rates (4). Obesity is a significant risk factor not only in the development of primary malignancy of the liver, chiefly hepatocellular carcinoma (HCC), but also for colorectal cancer and colorectal liver metastases (CRLM) (5,6). The liver surgeon can, therefore, expect to encounter increasing numbers of obese patients requiring hepatectomy going forward. Obesity itself can present challenges to the surgeon, not least by limiting exposure and increasing the technical difficulty of a procedure, but also by complicating access techniques to the abdominal cavity for minimally invasive surgery (MIS). Of particular concern to the surgeon is that parenchymal dissection in the presence of NAFLD can prove problematic, with higher rates of intra-operative blood loss than for those without NAFLD (7). Excess blood loss, and sarcopaenic obesity, have been shown to be risk factors for post operative bile leakage, likely reflecting poorer quality parenchyma and increasing technical difficulty of resection (8). The effect of obesity on liver quality can be compounded by the presence of chemotherapy-associated steatohepatitis (CASH) for patients with CRLM, with irinotecan in particular associated with increased steatohepatitis, with negative impacts on patient outcomes and mortality risk (9). Some authors have found higher rates of post-hepatectomy liver failure (PHLF) following liver resection in obese patients or those with NAFLD, but this has not been shown by Kampf et al. in their paper in this journal (10). They retrospectively evaluated 888 patients undergoing elective liver resection for all causes in their centre and examined the impact of increased BMI (both overweight and obese) primarily on the incidence of PHLF, but also on overall morbidity, mortality, and the incidence of non-alcoholic steatohepatitis (NASH). Unsurprisingly, obesity was associated with significantly higher rates of NASH (41.3%) than seen in overweight (23.3%) or normal weight (16.1%) patients (P3 segments) [odds ratio (OR) 2.8, 95% confidence interval (CI): 1.87–4.27; P