Obesity paradox as a new insight from postoperative complications in gastric cancer

Abstract

The obesity paradox is reported to exist in various diseases. However, obesity is a pivotal issue in gastric cancer (GC) patients because of the surgical difficulty related to postoperative abdominal infectious complications (PAIC). This study clarified the existence of the obesity paradox in GC. Between 1997 and 2015, 1536 consecutive patients underwent curative gastrectomy. Of all patients, 18.6% (285/1536) were obese and tended to have a better prognosis (P = 0.073). In patients without PAIC, obesity was a significant prognostic factor for 5-year overall survival (P = 0.017). PAIC was an independent poor prognostic factor in both obese and non-obese patients (P < 0.001; hazard ratio [HR] 4.22 and 1.82). In pStage II-III patients, there was a large and significant prognostic difference between non-PAIC and PAIC obese patients (P = 0.006; 5-year overall survival: 69.7% vs. 43.8%) related to the higher incidence of peritoneal recurrence in PAIC obese patients (P = 0.035; 31% vs. 10%). Whereas, there was a small prognostic difference between non-PAIC and PAIC non-obese patients (P = 0.102; 5-year overall survival: 56.5% vs. 51.9%). Although the obesity paradox is present in GC, PAIC had a more negative prognostic impact through peritoneal recurrence in obese GC patients.

Figure 1

(a) Survival curves for all patients. There was no prognostic difference between obese and non-obese patients (P = 0.073). (b) Survival curves according to pStage. There was no prognostic difference between obese and non-obese patients (P = 0.241, P = 0.148). (c) Survival curves for patients without postoperative abdominal infectious complications (PAIC) according to a BMI cut-off value of 25. Obese patients had a significantly better prognosis than non-obese patients (P = 0.017).

Figure 2

Overall survival curves according to the combination of PAIC and obesity status. In 499 consecutive patients with pStage II–III GC, there was a large and significant prognostic difference between non-PAIC and PAIC obese patients (P = 0.006; 5-year overall survival: 69.7% vs. 43.8%), related to the higher incidence of peritoneal recurrence in PAIC obese patients (P = 0.035; 31.2% vs. 9.5%). In contrast, there was a small prognostic difference between non-PAIC and PAIC non-obese patients (P = 0.102; 5-year overall survival: 56.5% vs. 51.9%).

Figure 3

Peritoneal recurrence rates in patients with pStage II–III GC according to the combination of obesity and PAIC. In 499 consecutive patients with pStage II–III GC, obese patients with PAIC were more likely to relapse with peritoneal recurrence than patients without PAIC (P = 0.035; 31.2% vs. 9.5%).

Figure 4

Comparison of postoperative serum CRP level according to the combination of PAIC and obesity status. Obese patients with PAIC had significantly higher serum CRP level than obese patients without PAIC, non-obese patients with PAIC, and non-obese patients without PAIC (P < 0.001; 18.5 vs. 16.4 vs. 11.8 vs. 11.6 mg/L) on postoperative day 3. The results were similar on postoperative day 5 (P < 0.001; 14.2 vs. 11.9 vs. 6.3 vs. 5.4 mg/L) and day 7 (P < 0.001; 11.6 vs. 11.3 vs. 3.9 vs. 3.4 mg/L).