Obesity and Cancer
Cancer, in its simplest form, can be described as uncontrolled cell proliferation. Cells multiplying uncontrollably cause disease in the organ or tissue they are in. Growth and proliferation are coordinated by some intracellular and intercellular signals. This coordination is in close relationship with the signals necessary for food coordination. Obesity, as a state of nutrient excess, activates cellular growth in several ways. Excess nutrient is stored in the organism as fat. Adipose tissue chronically transmits the signal of nutrient excess (increased leptin levels, decreased adiponectin levels). This chronic activation causes chronic inflammation and ultimately increases the risk of cells becoming cancerous. Apart from this, obesity contributes to the synthesis of some steroidal hormones; It contributes to tumor cell formation via insulin metabolism and growth factors and by activating many other oncogenic signaling pathways. The basic pathology appears to be chronic inflammation occurring in the body due to increased adipose tissue, and a secondary increased cancer tendency (1).
By the International Agency for Research on Cancer (IARC) hepatocellular carcinoma (liver), exocrine pancreas, gallbladder, cholangiocarcinoma (biliary tract), colorectal, renal (kidney), esophagus and stomach cardia adenocarcinoma, prostate, postmenopausal breast, endometrium, ovary, thyroid cancer and multiple myeloma cancers have been associated with obesity. Studies have shown that melanoma and skin cancers, which were previously assumed not to be associated with obesity, may be associated with obesity (2). Obesity is second only to tobacco use as a modifiable risk factor for cancer. In parallel with the increasing prevalence of obesity in young individuals, the incidence of cancer is expected to increase in the coming years. It is estimated that obesity alone accounts for 20% of all cancer causes. Obesity has been found to be a cause of 14% of cancer deaths in men and up to 20% of cancer deaths in women (3,4).
Cancer patients with a BMI greater than 40 had higher cancer mortality rates (52% higher for men and 62% higher for women) compared to normal weight cancer patients. (5). It is known that losing weight reduces the risk of cancer. Today, the only long-term and effective treatment for obesity is surgery. It has been shown that bariatric surgery is associated with a decrease in obesity-related cancer risk (6). There are publications showing that bariatric surgery also reduces the risk of cancer that is not associated with obesity. It has been found that obese individuals who have undergone bariatric surgery have a 33% lower risk of developing cancer compared to obese patients who have not undergone bariatric surgery (7).