Metabolic syndrome and cancer: "The common soil hypothesis".

Metabolic syndrome (MetS) and cancer share many modifiable risk factors including age, genetic factors, obesity, physical inactivity, unhealthy diet, alcohol, smoking, endocrine disruptors exposure, circadian clock disturbances, and air pollution. MetS is closely linked to cancer, as it increases cancer risk and cancer-related mortality; moreover, cancer survivors have an increased risk of MetS. Elucidating the mechanisms linking MetS to cancer is important to prevent or delay these two conditions. Possible mechanisms explaining the relationship between MetS and cancer include hyperinsulinemia and alterations of insulin-like growth factor system, chronic subclinical inflammation, abnormalities in sex hormones metabolism and adipokines, hyperglicemia, alterations in both gene expression and hormonal profile by endocrine disruptors and air pollution, desynchronization of circadian clock. The common soil hypothesis claims that MetS may be considered a surrogate marker for dietary risk factors of cancer, and a warning sign for susceptible individuals exposed to an unhealthy diet. The common soil hypothesis and the clepsydra of foods represent a theoretical substrate to preventive intervention strategies against the pandemics of MetS and cancer: adherence to healthy dietary patterns is associated with a reduced risk of MetS, and improvement of the quality of diet is consistently associated with a reduction in cancer-related mortality.