Supplementary Material for: Consumption of Sugar-sweetened Soft Drinks and Risk of Gastrointestinal Cancer: A Systematic Review and Meta-analysis of Observational Studies

Introduction: Previous observational studies have reported inconsistent findings on the association between consumption of sugar-sweetened soft drinks (SSSDs) and the risk of gastrointestinal (GI) cancer. This study investigated the associations between SSSD consumption and the risk of GI cancer using a systematic review and meta-analysis.
Methods: Observational epidemiological studies were searched from the PubMed and EMBASE databases until June 2021. We conducted a meta-analysis of all included studies and subgroup meta-analyses based on various factors.
Results: In a meta-analysis of 27 studies with nine case-control studies and 18 cohort studies, the consumption of SSSDs was modestly associated with an increased risk of GI cancer (OR/RR: 1.08; 95% CI, 1.01-1.16), with a significant positive dose-response relationship. In the subgroup meta-analysis by study design, there was a significant positive association between the consumption of SSSDs and GI cancer in cohort studies (RR, 1.11; 95% CI, 1.03-1.20; n = 18), but not in case-control studies. In the subgroup meta-analysis by type of cancer, consumption of SSSDs was significantly associated with an increased risk of colorectal cancer (OR/RR: 1.13; 95% CI, 1.07-1.19).
Conclusions: This meta-analysis suggests that SSSD consumption significantly increases the risk of GI cancer, specifically colorectal cancer.