A sedentary lifestyle is associated with a 77% increased risk of kidney cancer and a 73% increased risk of bladder cancer independent of obesity and other health lifestyle factors.
Several biological mechanisms have been proposed to account for an association between physical inactivity and cancer. These include an increase in circulating levels of sex hormones, increased chronic inflammation, impaired insulin sensitivity, impaired immune surveillance and responsiveness, increased adiposity, and a dysregulated adipokine milieu.
While this study found the association between physical inactivity and increased cancer risk to be independent of obesity, many other studies have found that obesity increases cancer risk as well. There are many lifestyle factors that can modulate cancer risk including diet, obesity, exercise, smoking, and excess alcohol consumption.