Table 1.

Ten Takeaway Messages: Obesity and Cancer. Obesity is a leading cause of cancer. ROS: reactive oxygen species.

1.	Obesity is the second most common preventable cause of cancer and may soon overtake cigarette smoking as the most common preventable cause of cancer [15]. For nonsmokers, obesity is considered the single most common preventable cause of cancer, especially when accompanied by unhealthful nutrition and physical inactivity.
2.	Among U.S. adults, the proportion of cancers attributable to excess body weight is ∼5% for men and ∼10% for women; an increase in body weight may be contributing to an increase in cancer among young adults [16,17].
3.	No drug has an indication to treat both obesity and prevent/treat cancer.
4.	Adiposopathic consequences of obesity that promote cancer include adipose tissue cytokine production (e.g., tumor necrosis factor, interleukin-6) which may damage cellular DNA, promote gene mutations, enhance angiogenesis, promote cell proliferation, and contribute to mitochondrial and endoplasmic reticulum stress, increasing reactive oxygen species (ROS) which may further damage cellular DNA [[18], [19], [20], [21]].
5.	Adiposopathic hypoxia processes that may promote cancer include growth of adipocytes and adipose tissue beyond their vascular supply, increasing immune and angiogenic responses, accelerating the growth and progression of cancer [22]. Obesity-related sleep apnea, and its associated hypoxia, may be associated with increased cancer risk [23,24].
6.	Obesity, adiposopathy, cigarette smoking, physical inactivity, and reduced intake of antioxidant- and phytochemical-rich foods may facilitate carcinogenic oxidative stress, which is the imbalance in the creation of unstable reactive oxygen species (ROS) relative to the body's ability to detoxify these radicals [2,20,21]. ROS contributes to carcinogenesis.
7.	Additional adiposopathic adverse consequences of increased cytokine production include endothelial dysfunction, extracellular matrix abnormalities, and intravasation, which is the movement of cells from a tissue through a vessel wall into the circulation, and which is the rate limiting step of metastasis [18,22].
8.	Adiposopathic endocrine processes that promote cancer include increased cancer promoting hormones, such as estrogens, leptin, androgens in women, and growth hormones (i.e., insulin-like growth factor-1) [18]. Insulin has a high degree of homology with insulin-like growth factor, and the hyperinsulinemia of insulin resistance (often found with obesity) may play a role in tumorigenesis [25,26].
9.	Beyond their effects on body fat accumulation, foods that may increase the risk of cancer include processed meats, meats cooked at high temperature, and simple carbohydrates including sugar-sweetened beverages [27]. Among foods that may decrease the risk of cancer are whole foods rich in phytochemicals, fiber, and antioxidants (e.g., citrus fruits, cruciferous and green leafy vegetables, legumes, nuts, whole grains, and some coffees and teas) [28,29]. Physical activity may reduce proinflammatory responses and help normalize insulin and sex hormone levels, potentially reducing cancer risk.
10.	Among patients with obesity, weight reduction, as well as appropriate nutrition and physical activity may help prevent cancer, enhance the efficacy of chemotherapy for cancer, and reduce the risk of recurrent cancer [20].