Obesity is now one of the leading causes of cancer. New findings about how obesity connects to cancer growth may help prevent cancer and help survivors.
BETHESDA, MD — Being at a healthy weight is the most important thing people can do to prevent cancer, after not smoking, according to research presented today at the American Institute for Cancer Research (AICR) Annual Research Conference.
Yet, experts said, too many Americans remain unaware of the link.
“As time goes on, we are finding that obesity appears to be playing a role in more and more cancers,“ said session co-chair Wendy Demark-Wahnefried, PhD, RD, a nutrition scientist at the University of Alabama at Birmingham Comprehensive Cancer Center. “It not only affects primary risk, but also prognosis and survival.”
A 2013 AICR survey found that less than half of Americans – 48 percent – are aware that overweight and obesity link to higher cancer risk. That’s a drop in awareness from its 2009 high of 51 percent, and represents the first time awareness of this major cancer risk has dropped since the survey began in 2001.
AICR estimates that carrying excess body fat will cause approximately 117,000 cases of cancer in the United States this year. Overweight and obesity are specifically linked to many of the most common cancers: colorectal, post-menopausal breast, esophageal, endometrial, kidney, pancreatic and gallbladder.
The latest government statistics show that approximately two thirds of US adults are overweight or obese; one third of children are overweight or obese.
Connecting Obesity to Cancer Growth
Studies by Stephen D. Hursting, PhD, Professor and Chair of the Department of Nutritional Sciences at University of Texas at Austin, have identified several potential pathways by which obesity promotes cancer. Animal studies by Hursting and his colleagues have found that obesity alters levels of insulin and other hormones, regulators of inflammation and the health of blood vessels.
“Our research suggests that obesity-induced changes in interrelated metabolic, inflammatory and vascular pathways represent possible targets for disrupting the obesity-cancer link,” said Hursting.
Another animal study by Hursting and his colleagues reveals how breast cancer stem cells (cells that may be responsible for initiating a breast tumor) may be thwarted by depriving them of leptin, a hormone produced by fat cells. The amount of leptin in the body increases with obesity, and breast cancer stem cells appear to need leptin to survive and grow.
“One of the leptin-related factors, called ’NANOG,’ contributes to the growth of several cancers,” Hursting said. “We are now studying if suppressing it by inhibiting leptin receptors will eventually lead to a treatment that suppresses tumor growth.
“Knowing what cancer-related processes in the body change because of obesity offers us exciting opportunities for breaking the link between obesity and cancer.”
Other research on the obesity-cancer link presented at today’s session highlighted:
- How obesity contributes to breast cancer, presented by Pamela J. Goodwin, MD, MSc, FRCPC, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto.
- How obesity may increase prostate risk and lead to worse outcomes among survivors, presented by Elizabeth Platz, ScD, MPH, Johns Hopkins Bloomberg School of Public Health in Baltimore
- Comparing the role of diet, weight and lifestyle in cancer risk and prognosis, presented by Jennifer A. Libigel, MD, Harvard Medical School, Dana-Farber Cancer Institute
To the Editors
- Hursting SD, DiGiovanni J, Dannenberg AJ, Azrad M, LeRoith D, Brodie A, Demark-Wahnefried W, Berger NA. Obesity, energy balance and cancer: new opportunities for prevention. Cancer Prev Res 2012; 5:1260-72.
- Zheng Q, Banaszak L, Fracci S, Basali D, Dunlap SM, Hursting SD, Rich JN, Hjlemeland AB, Vasanji A, Berger NA, Lathia JD, Reizes O. Leptin receptor maintains cancer stem-like properties in triple negative breast cancer cells. Endocrine Related Cancer. 14 October 2013.
- 2013 AICR Cancer Risk Awareness Survey, American Institute for Cancer Research.
- Centers for Disease Control and Prevention. Obesity and Overweight. Lashinger LM, Harrison LM, Rasmussen AJ, Logsdon CD, Fischer SM, McArthur MJ, Hursting SD. Dietary energy balance modulation of Kras- and Ink4A/Arf+/–driven pancreatic cancer: the role of insulin-like growth factor-1. Cancer Prev Res 2013; 6:1046-55.
- Hursting SD, DiGiovanni J, Dannenberg AJ, Azrad M, LeRoith D, Demark-Wahnefried W, Kakarala M, Brodie A, Berger NA. Obesity, Energy Balance and Cancer: New Opportunities for Prevention. Cancer Prev 5:1260-72, 2012.