Premorbid Obesity and Mortality in Patients With Pancreatic Cancer: A Systematic Review and Meta-analysis

Abstract

Background & aims: Obesity is associated with an increased risk for pancreatic cancer, but it is unclear whether it affects mortality. We performed a systematic review and meta-analysis to assess the association between premorbid obesity and mortality from pancreatic cancer.

Methods: We performed a systematic search through January 2015 and identified studies of the association between premorbid obesity (at least 1 year prior to pancreatic cancer diagnosis) and pancreatic cancer-related mortality. We estimated summary adjusted hazard ratio (aHR) with 95% confidence interval (CI), comparing data from obese (body mass index [BMI] ≥30 kg/m(2)) and overweight subjects (BMI, 25.0-29.9 kg/m(2)) with those from individuals with a normal BMI (controls) by using random-effects model.

Results: We identified 13 studies (including 3 studies that pooled multiple cohorts); 5 studies included only patients with pancreatic cancer, whereas 8 studies evaluated pancreatic cancer-related mortality in cancer-free individuals at inception. In the meta-analysis, we observed increase in pancreatic cancer-related mortality among overweight (aHR, 1.06; 95% CI, 1.02-1.11; I(2) = 0) and obese individuals (aHR, 1.31; 95% CI, 1.20-1.42; I(2) = 43%), compared with controls; the association remained when we analyzed data from only subjects with pancreatic cancer. Each 1 kg/m(2) increase in BMI was associated with 10% increase in mortality (aHR, 1.10; 95% CI, 1.05-1.15) with minimal heterogeneity (I(2) = 0). In the subgroup analysis, obesity was associated with increased mortality in Western populations (11 studies; aHR, 1.32; 95% CI, 1.22-1.42) but not in Asia-Pacific populations (2 studies; aHR, 0.98; 95% CI, 0.76-1.27).

Conclusions: In a systematic review and meta-analysis, we associated increasing level of obesity with increased mortality in patients with pancreatic cancer in Western but not Asia-Pacific populations. Strategies to reduce obesity-induced metabolic abnormalities might be developed to treat patients with pancreatic cancer.

Keywords: Adiposity; Malignancy; Pancreas; Survival.

Figure 1

Flow sheet summarizing study identification and selection. OR, short of odds ratio; PaC, pancreatic cancer; RR, relative risk.

Figure 2

(A) Summary of maximally adjusted HR for association between premorbid BMI and pancreatic cancer-related mortality, comparing patients in the highest category of BMI with the lowest category. The size of the box corresponds to the weight of the given study. (B) Summary of maximally adjusted HR for association between premorbid BMI and pancreatic cancer-related mortality, comparing overweight (BMI 25.0–29.9 kg/m²) and obese (BMI ≥30 kg/m²) patients with normal BMI patients. The size of the box corresponds to the weight of the given study. (C) Summary of maximally adjusted HR for evaluation of dose-response relationship between premorbid BMI and pancreatic cancer–related mortality. The estimate represents mortality increase per 1 kg/m² increase in BMI. SE, standard error.