Cancer can be simply defined as uncontrolled cell proliferation. Uncontrolled proliferating cells cause disease in the organs or tissues where they reside. Growth and multiplication are coordinated by certain intracellular and intercellular signals. This coordination is closely related to signals necessary for nutrient coordination. Obesity, characterized by excess nutrition, activates cellular growth through various pathways. Excess nutrients are stored in the body as fat. Adipose tissue chronically transmits the signal of nutrient excess (with increased leptin levels and decreased adiponectin levels). This chronic activation leads to chronic inflammation and ultimately increases the risk of cellular transformation into cancer. Additionally, obesity contributes to the synthesis of certain steroid hormones and activates numerous oncogenic signaling pathways through insulin metabolism and growth factors, aiding in the formation of tumor cells. The underlying pathology seems to be chronic inflammation occurring in the body due to increased adipose tissue and, secondarily, an increased cancer propensity (1).

The International Agency for Research on Cancer (IARC) has found associations between obesity and various cancers, including hepatocellular carcinoma (liver), exocrine pancreas, gallbladder, cholangiocarcinoma (bile duct), colorectal, renal (kidney), esophagus, gastric cardia adenocarcinoma, prostate, postmenopausal breast, endometrium, ovary, thyroid cancer, and multiple myeloma. Studies have also suggested that melanoma and skin cancers, previously thought not to be related to obesity, may indeed have a connection (2). Obesity ranks second as a modifiable risk factor for cancer, following tobacco use. As the prevalence of obesity increases among young individuals, a rise in cancer incidence is expected in the coming years. It is estimated that obesity accounts for 20% of all cancer causes on its own. Obesity has been identified as a contributing factor in 14% of cancer deaths in men and up to 20% in women (3,4). Cancer patients with a body mass index (BMI) over 40 have been found to have higher cancer mortality rates compared to normal-weight cancer patients (52% higher in men and 62% higher in women) (5).

It is known that weight loss reduces cancer risk. Currently, the only long-term and effective treatment for obesity is surgery. Bariatric surgery has been shown to be associated with a reduction in cancer risk related to obesity (6). There are also publications indicating that bariatric surgery reduces the risk of cancers not associated with obesity. Individuals who have undergone bariatric surgery have a 33% lower risk of developing cancer compared to obese patients who have not undergone the procedure (7).