One Step to Prevent Breast Cancer

Weight Loss Surgery Beats Diet at Inhibiting Breast Cancer

Article Critique by Alexa Judy, UCSN2

Alexa Judy is a second-year nursing student at the University of Cincinnati's College of Nursing. She is currently enjoying her courses in Nutrition, Pharmacology, and Advanced Fundamentals and her clinical experience at the University of Cincinnati Medical Center on 7 NW, a medical-surgical unit. The topic of cancer and cancer research greatly interest her, since many cancers run in her family. She would love to expand her knowledge of the ways cancer can be prevented in those who are predisposed to certain types.

ARTICLE: Weight loss surgery was more effective than a low-fat diet at reversing the cancer-promoting effects of chronic obesity in mice, report UNC Lineberger Comprehensive Cancer Center researchers.

"Our basic finding was that surgical weight loss in obese mice was able to inhibit mammary tumor growth in a mouse model of basal-like breast cancer, while weight loss induced by a low fat, low calorie diet was not," said Emily Rossi, the paper's first author and a pre-doctoral trainee with the UNC Lineberger Cancer Control and Education Program.

Rossi and her colleagues in the lab of Stephen Hursting, PhD, MPH, a UNC Lineberger member and professor of nutrition in the UNC Gillings School of Global Public Health and the UNC Nutrition Research Institute, are leading research to understand and potentially break the link between obesity and cancer.

"Data from human studies has suggested that there is something mechanistically different about bariatric surgery, relative to diet-induced weight loss, that makes the surgery more effective at preventing or controlling breast cancer," Hursting said. "Now that we have (for the first time) replicated this surgery versus diet effect in an experimental model of breast cancer, we have the opportunity to determine the molecular and metabolic factors that are responsible for the protective effects of the surgery."

Obesity is a significant risk factor for several types of breast cancer, including basal-like breast cancer subtype. Rossi, Hursting and their colleagues have shown in previous research that obesity reversal through diet may not be enough to reverse the effects of chronic obesity on molecular drivers of cancer, including epigenetics and inflammation.

In the most recent preclinical study, mice were either fed a low-fat diet or an obesity-promoting high-fat diet for 15 weeks. Obese mice were then randomized to a weight loss surgical procedure called a sleeve gastrectomy, in which the surgeon removes a large portion of the stomach, or to lose the same amount of weight through a low-fat diet.

Rossi and her colleagues found that tumor growth in obese mice that had the weight loss surgery was statistically equivalent to mice that had maintained a normal weight, but obese mice that lost weight through a low-fat diet had less anti-cancer benefit. Tumor growth in the mice who lost weight by diet mirrored the tumor growth seen in obese mice.

Surgical weight loss was also linked to lower levels of certain molecular drivers of cancer. Mice that went through surgical weight loss had lower levels of insulin and inflammatory proteins, suggesting that the surgery reduced obesity-linked increases in insulin, inflammation and breast cancer growth.

"One consequence of the obesity epidemic in the United States and many other countries is increasing rates of obesity-related cancer," Hursting said. "However, we are not going to solve this growing problem through bariatric surgery, which, despite being effective, is too expensive and too difficult to be done on everyone who is obese. Our goal is to understand what the surgery is doing metabolically to slow tumors, and replicate those protective effects through combinations of diet, exercise and possibly drugs that target some of the same pathways as the bariatric surgery."

In addition to Rossi and Hursting, other authors include Laura W. Bowers, Subreen A. Khatib, Laura A. Smith, and Steven S. Doerstling of the University of North Carolina at Chapel Hill; and Alfor Lewis and Randy J. Seeley of the University of Michigan.

L.W. Bowers and E.L. Rossi were supported by a grant from the National Cancer Institute (R25CA057726 Cancer Control and Education R25 training grant). S.D. Hursting is also supported by a grant from the National Cancer Institute (R35CA197627).

CRITIQUE:

The article “Weight Loss Surgery Beats Diet at Inhibiting Breast Cancer,” published on the website Science Daily on March 28th, 2016, was reprinted and edited from materials retrieved from the University of North Carolina Health Care System. The article speaks about bariatric surgery trials in mice that were found to have more inhibiting effects on mammary tumor growth than expected. Compared to mice that lost weight due to a low-fat, low-calorie diet, the mice that underwent bariatric surgery were found to have a lower incidence of breast cancer. The mice underwent a sleeve gastrectomy, which is removal of a larger portion of the stomach; the source believes that the outcomes of this procedure were linked to lower levels of insulin and inflammatory proteins, “suggesting that the surgery reduced obesity-linked increases in insulin, inflammation and breast cancer growth” (Science Daily, 2016).

The authors of the original text, Emily Rossi and Stephen Hursting, collaborated on this trial at the University of North Carolina at Chapel Hill. Emily L. Rossi is a graduate research assistant at UNC, who studies Nutritional Biochemistry and is particularly interested in bariatric surgery and its impact on mammary tumor growth. Stephen Hursting, Ph.D., M.P.H. is a nutrition professor at UNC, “interested in diet-gene interactions relevant to cancer prevention” (Hursting, n.d.). Other contributors of this study include Laura W. Bowers, Subreen A. Khatib, Laura A. Smith, and Steven S. Doerstling, all of the University of North Carolina at Chapel Hill, and Alfor Lewis and Randy J. Seeley from the University of Michigan. The National Cancer Institute, an organization that promotes cancer research and provides grants and training to those supporting their cause, sponsored both Emily Rossi and Stephen Hursting in their research.

I believe that this article is generally well written; however, the author jumps right into the research without providing any background information first, which could be misleading. Also, for readers who do not have a knowledge of cancer, the article may be difficult to comprehend and follow, considering the author and the quotes that the researchers provided include terminology such as “basal-like” and “epigenetics.” The author himself only demonstrates minimal knowledge of the topic; as a reader, I would find it helpful to have information regarding what exactly the “molecular drivers of cancer” are in order to better comprehend the article (Science Daily, 2016). Although the information presented in the article is based on scientific evidence obtained from a study performed by professional cancer researchers, I would have liked to know more about why bariatric surgery is more likely to prevent breast cancer than dieting and weight loss. The article simply stated the results of the study, not the rationale, which would have brought all of the information together into a logical piece of literature. Overall, I find this article to be interesting with scientific evidence to support the hypothesis, as well as credible sources providing the results of the study; however, I would not consider the article well written or sensible, even to professionals with a health literacy of this topic.

About the Researchers:

Emily L. Rossi

Emily Rossi is a Nutritional Biochemistry graduate research assistant at the University of North Carolina at Chapel Hill. She is greatly interested in bariatric surgery and its health benefits and spends much of her time performing clinical research.

Stephen Hursting, Ph.D., M.P.H.

Stephen Hursting is a Nutrition professor at the University of North Carolina at Chapel Hill. He does most of his research on diet-gene interactions in regards to cancer and cancer prevention, and is a member of Lineberger, a cancer research and treatment center at UNC at Chapel Hill.

Bibliography

Comprehensive Cancer Information. (n.d.). Retrieved April 06, 2016, from http://www.cancer.gov/

Rossi, E. L. (n.d.). Emily L Rossi. Retrieved April 06, 2016, from https://www.researchgate.net/profile/Emily_Rossi2

Stephen Hursting, Ph.D., M.P.H. (n.d.). Retrieved April 06, 2016, from http://www.uncnri.org/index.php/stephen-hursting-ph-d-m-p-h/

Weight loss surgery beats diet at inhibiting breast cancer. (2016, March 28). Retrieved April 06, 2016, from https://www.sciencedaily.com/releases/2016/03/160328121235.htm