Obesity and cancer

For the past several decades, we have witnessed the emergence of the obesity pandemic worldwide and, simultaneously, the increase of incidence of malignant diseases. The effects of obesity and overweight on cancer incidence, morbidity, and mortality started to be meticulously researched only recently. According to the epidemiological data analysis, the connection between obesity and increased risk of numerous cancers has been established. Estimations are that a change in lifestyle and diet can prevent 30-50% of malignant diseases. After smoking, obesity is the second largest preventable cause of cancer. Obesity affects the quality of life and increases the risk of cancer recurrence and cancer-related mortality. By reducing body mass and avoiding gaining weight during adulthood, the risk of getting cancer is lowered. Numerous studies have shown the beneficial effects of physical activity during and after cancer treatment. Obesity influences cancer development; however, the mechanisms responsible for it are still unclear. It is considered that chronic inflammation, caused by the overabundance of nutrients, increases the levels of inflammatory cytokines and immune cells. It has been discovered that adipocytes have an important endocrine role; they synthesize numerous hormones and adipocytokines, such as leptin and adiponectin. High levels of leptons and low levels of adiponectin can activate intracellular signaling pathways involving malignant cells’ development. An important part of cancer development can be attributed to insulin metabolism, insulin-like growth factors, and sex hormones.