Obesity and cancer progression
Obesity, which is a state of excess of nutrients, chronically activates cellular growth factor and metabolic signalling pathways and stimulates neoplastic transformation. Excess of adiposity has been identified as a risk factor for recurrence, reduced effectiveness and complications of the treatment, development of second primary tumor and mortality. Obesity is associated with the progression of various cancers and it is an important predictor of poor outcome of the disease. Several mechanisms have been proposed to link obesity with cancer. Quantity and quality of surrounding adipose tissue affect biological and secretory nature of adipocytes. Fatty acid metabolism plays significant role in the biology of cancer. Obesity causes alterations in adipose tissue microenvironment along with endocrinal imbalance that favors tumor initiation as well as progression. Tumor-promoting consequences of obesity occur via insulin resistance, dyslipedemia and inflamed adipose tissue that release local and systemic inflammatory mediators, Obesity worsens the progression of the disease affecting clinical course not only in relation to cancer outcome, but also other comorbid conditions. Improvement in the health of adipose tissue to reduce inflammatory state would be a novel therapeutic approach to minimize burden of cancer-related mortality. Hence in future, studies bridging the gap to connect preclinical experimental studies with human observations to evaluate impact of obesity on progression of different cancers are needed.