Association of obesity with the occurrence of Gastrointestinal cancer- A meta-analysis

Obesity is a risk factor for many diseases especially cancer. Numerous studies have been performed to examine the relation between obesity and different types of gastrointestinal cancer. However, involvement of obesity in overall gastrointestinal cancer risk is not very clear. Therefore, a meta-analysis was performed to investigate the association of obesity and overall gastrointestinal cancer risk. A thorough systematic search were performed on PubMed, MEDLINE and other databases and relevant studies were identified and scrutinised. A random effect model was used to calculate the correlation using risk ratio (RR) at 95% confidence interval. Publication bias was assessed by funnel plots. A total of 56 studies were used to perform meta-analysis. The pooled risk ratio calculated showed a significant relation between obesity and gastrointestinal cancer risk (RR = 1.742, 95% CI =1.54 - 1.96, P< 0.001). Subgroup analysis was also performed for different types of gastrointestinal cancer such as oesophageal cancer, stomach cancer, liver cancer, pancreatic cancer, and colorectal cancer. The pooled risk ratio for each type of gastrointestinal cancer was found to be RR = 2.376 (oesophageal cancer), RR = 1.131 (stomach cancer), RR = 1.976 (liver cancer), RR = 1.474 (pancreatic cancer), and RR = 1.428 (colorectal cancer). There was observed no significant bias in the study. This study suggested that obesity is significantly associated with risk of gastrointestinal cancer especially oesophageal cancer. However, further investigations and large clinical trials are required to make an impactful and conclusive statement about this association.