Obesity as a Risk Factor for Various Cancers: A Systematic Review

Obesity is often assessed through body mass index (BMI), which is a ratio of body weight to height, as defined by the World Health Organization (WHO). Several studies have shown a clear association between obesity and an increased risk of several cancers, including esophageal adenocarcinoma, breast cancer in postmenopausal women, pancreatic cancer, colorectal cancer, endometrial cancer, kidney cancer, and liver cancer. This review aims to synthesize the available evidence on obesity as a risk factor for different types of cancer. The articles in this review were selected using the PubMed database and EBSCO information services, focusing on the articles that were most relevant to the topic. Articles unrelated to the subject were excluded. The data were extracted following a specific protocol. Obesity is a key risk factor for the development and progression of various types of cancer, especially gastrointestinal cancers such as colorectal, gastric, and liver cancer. This association is attributed to various pathophysiological mechanisms, including impaired immune function in obese individuals. However, in some cases, the evidence linking obesity to cancer risk is not conclusive, and factors such as gender may influence how obesity acts as a risk factor for cancer.