Obesity and Cancer
Obese people often have chronic low-level inflammation, which can, over time, cause DNA damage that leads to cancer. Overweight and obese individuals are more likely than normal-weight individuals to have conditions or disorders that are linked to or that cause chronic local inflammation and that are risk factors for certain cancers. For example, chronic local inflammation induced by gastroesophageal reflux disease or Barrett esophagus is a likely cause of esophageal adenocarcinoma. Obesity is a risk factor for gallstones, a condition characterized by chronic gallbladder inflammation, and a history of gallstones is a strong risk factor for gallbladder cancer.
Fat tissue (also called adipose tissue) produces excess amounts of estrogen, high levels of which have been associated with increased risks of breast, endometrial, ovarian, and some other cancers.
Obese people often have increased blood levels of insulin and insulin-like growth factor-1 (IGF-1). (This condition, known as hyperinsulinemia or insulin resistance, precedes the development of type 2 diabetes.) High levels of insulin and IGF-1 may promote the development of colon, kidney, prostate, and endometrial cancers.
Obesity increases an individual’s risk of developing many types of cancer, including colorectal cancer. One of the factors driving the rise in obesity rates is thought to be the use of high-fructose corn syrup (HFCS) as a sweetener in soft drinks.
One soft drink a day could increase your risk of cancer
A new study by Cancer Council Victoria and the University of Melbourne analysed more than 35,000 Victorians over a twelve year period who developed 3,283 cases of obesity-related cancers including liver, ovary, pancreas and gallbladder.
This research, from Cancer Council Victoria’s Cancer Epidemiology and Intelligence Division and University of Melbourne’s Centre for Epidemiology and Biostatistics, looked at whether more frequent consumption of sugar-sweetened soft drinks would be associated with increased risk of 11 obesity-related cancers:
- Aggressive prostate
- Postmenopausal breast
- Gastric cardia
Artificially sweetened soft drinks were also assessed for comparison. The research found that higher consumption of both sugar-sweetened and artificially sweetened soft drinks was associated with higher waist circumference, although cancer risk was only higher among those who drank more sugar-sweetened soft drinks.
High-fructose corn syrup (sweetener in soft drinks) enhances intestinal tumor growth in mice
Does sugar directly feed cancers, boosting their growth? The answer seems to be ‘Yes’ at least in mice according to a study led by researchers at Baylor College of Medicine and Weill Cornell Medicine. Their study, published in Science, showed that consuming a daily modest amount of high-fructose corn syrup — the equivalent of people drinking about 12 ounces of a sugar-sweetened beverage daily — accelerates the growth of intestinal tumors in mouse models of the disease, independently of obesity. The team also discovered the mechanism by which the consumption of sugary drinks can directly feed cancer growth, suggesting potential novel therapeutic strategies.
In this study, it has been found that HFCS, the primary sweetener used in SSBs, contributes to intestinal tumorigenesis in mice by accelerating glycolysis and de novo lipogenesis. These effects are independent of obesity and metabolic syndrome. HFCS in liquid form rapidly increases the levels of fructose and glucose in the intestinal lumen and serum, respectively, which allows intestinal tumors to take up these sugars for their growth.
The study also provides important preclinical evidence that the combination of dietary glucose and fructose, even at moderate dose, can enhance intestinal tumor growth. Whether these findings can be extrapolated to humans requires further investigation.