Body Mass Index and Cancer Risk: An Umbrella Review of Meta-Analyses of Observational Studies.
Level 3 - non-randomized controlled study
Umbrella review of systematic reviews and meta-analyses of observational studies
PubMed 37139871 · doi:10.1080/01635581.2023.2180824
What was done
Authors conducted an umbrella review of systematic reviews and meta-analyses searched via PubMed, Embase, and Web of Science to evaluate the associations between body mass index (BMI) categories (underweight, overweight, obesity) and cancer incidence. Eighteen meta-analyses of observational studies met inclusion criteria, with 10 providing dose-response data.
What was found
Underweight was inversely associated with brain tumor incidence and positively associated with risks of esophageal and lung cancer. Overweight was linked to increased incidence of brain, kidney, endometrial, ovarian, bladder, and liver cancers, and multiple myeloma. Obesity was linked to higher incidence of 14 cancer types: brain, cervical, kidney, endometrial, esophageal, gastric, ovarian, multiple myeloma, gallbladder, bladder, colorectal, liver, thyroid, and Hodgkin's lymphoma. In dose-response analyses (10 studies), each 5 kg/m² increase in BMI was associated with a 1.01- to 1.13-fold increase in risk for brain tumors, multiple myeloma, bladder, pancreatic, breast cancer, and non-Hodgkin's lymphoma. Each 1 kg/m² increase in BMI was associated with a 6% and 4% risk increase for kidney and gallbladder cancers, respectively. Point estimates and confidence intervals for the categorical associations were not reported in the abstract.
Why it matters
This synthesis provides comprehensive broad-spectrum mapping of BMI-related oncologic risk across organ systems, reinforcing the relevance of adiposity management in population-level cancer prevention strategies.
Limits
All included evidence comes from observational studies, preventing causal inference and leaving susceptibility to residual confounding (e.g., smoking, diet). The abstract lacks total individual participant numbers, effect sizes and confidence intervals for categorical outcomes, and details on primary study overlap between included meta-analyses.
Cited by
- supports Obesity is established in scientific research as being linked to an increased risk of cancer.