Obese patients are at an increased risk of numerous medical problems, such as diabetes mellitus, hypertension and immune dysfunction, which can adversely affect the surgical outcomes. However, several studies have investigated this issue and the results are still controversial, possibly due to the use of different definitions and classifications of obesity, and the lack of a uniform way of reporting surgical complications[16,17
]. Dindo et al[6
] studied the impact of obesity (BMI ≥ 30 kg/m2
) on the outcomes of 6336 patients undergoing general elective surgery. They found that obesity alone was not a risk factor for postoperative complications. Since the association between BMI and health risks to Asian populations is different from that in European populations[11,18
], we defined obesity as BMI ≥ 25 kg/m2
in this study. Consistent with the findings of a previous report[6
], there was no significant difference in the incidence of postoperative complications and postoperative hospital death between the non-obese group (BMI < 25 kg/m2
) and the obese group (BMI ≥ 25 kg/m2
), following curative hepatectomy in patients with primary HCC. On the other hand, among patients with recurrent HCC, the operation time and blood loss were significantly greater in the obese group than in the non-obese group. Since the operative procedures (extent of hepatic resection) were comparable between the two groups (Table ), these data reflect the apparent greater technical difficulty of a repeat hepatectomy in obese patients. The wider area of peritoneal adhesion owing to the previous operation and the limited visualization of the surgical field in obese patients might adversely affect the operation time and blood loss. However, the difference in the incidence of postoperative complications after a repeat hepatectomy between the two groups did not reach statistical significance. Therefore, these results indicate that there exists no marked influence of obesity (BMI ≥ 25 kg/m2
) on the early surgical outcome after a curative hepatic resection, in both patients with primary HCC and those with recurrent HCC.
Only a few investigators have studied the impact of obesity on long-term outcomes following surgery, and the results are conflicting[3,19
]. Dhar et al[3
] suggested that being overweight was an independent predictor of disease recurrence in T2/T3 gastric cancers, whereas Kodera et al[19
] reported that obesity did not affect long-term survival after a distal gastrectomy in gastric cancer patients. In the current study, we found no remarkable impact of obesity on the long-term prognosis after a curative hepatectomy in patients with primary HCC. On the other hand, among patients with recurrent HCC, the long-term prognosis following repeat hepatectomy in the obese patients was significantly worse than that in the non-obese patients. Furthermore, obesity (BMI ≥ 25 kg/m2
) was an independent poor prognostic indicator in patients with recurrent HCC. The reason why obesity adversely affects the long-term outcome in these patients is not clear. However, several reports have suggested that obesity is significantly associated with a higher rate of death due to many cancers, including liver cancer[12,13,20,21
]. In particular, recent studies have implicated that non-alcoholic steatohepatitis (NASH), which is characterized by obesity, can progress to liver cirrhosis and HCC[22–24
]. However, pathological examinations in the resected non-cancerous liver specimens revealed only 4 of the 328 patients with primary HCC and one of the 60 patients with recurrent HCC to have NASH in this study. It therefore appears that the poorer prognosis after repeat hepatectomy in obese patients was not attributable to the progression of NASH. The mechanism generally proposed to explain the association between obesity and a worse prognosis include elevated concentrations of insulin-like growth factors[25
] and cytokines[28
]. Additional proposed mechanisms include reduced immune functioning and differences in diet and physical activity between obese and non-obese patients[20,21
]. However, these mechanisms fail to explain the poorer prognosis after a repeat hepatectomy in the obese patients, because such a worse prognosis was not observed in obese patients with primary HCC. Among patients with recurrent HCC, those in the obese group showed a significantly greater amount of blood loss and tended to receive blood transfusions more frequently than those in the nonobese group. Many investigators have demonstrated that the increased blood loss and the need for blood transfusions are risk factors for recurrent HCC[29,30
], which is attributed to the induction of immunosuppression. Therefore, the worsened prognosis in obese patients might be associated with the synergistic impacts of the obesity itself and perioperative blood transfusions due to increased blood loss on immune function.
In conclusion, our present findings suggest that the obesity, as defined by a BMI ≥ 25 kg/m2, does not have an adverse impact on postoperative outcomes, including postoperative complications and long-term prognosis, after a curative hepatectomy in patients with primary HCC. However, more caution seems to be required when planning a repeat hepatectomy for recurrent HCC in patients who are either overweight or obese.