ASCO Obesity Initiative: How Does Obesity Affect Cancer Outcomes?

Jennifer A. Ligibel, MD

Today, ahead of the American Society of Clinical Oncology (ASCO) Annual Meeting held May 29 to June 2 in Chicago, we are speaking with Jennifer Ligibel, MD, an assistant professor at Harvard Medical School and a senior physician in the women’s cancer program at Dana-Farber Cancer Institute in Boston. Dr. Ligibel will be discussing ASCO’s obesity initiative at the meeting in a session that talks about the link between cancer, obesity, and exercise.

 -Interviewed by Anna Azvolinsky 

Cancer Network: Can you tell us about ASCO’s obesity initiative?

Dr. Ligibel: Sure. About 2 years ago in recognition of the growing rates of obesity in the United States and beyond, as well as the emerging evidence that obesity and related factors like inactivity and poor dietary quality are linked not only to the risk of developing cancer but also to the risk of recurrence and overall mortality in individuals with cancer, ASCO launched the first Energy Balance Work Group that was designed to look at the evidence linking obesity and related factors to cancers and to start to develop some priorities around this topic. They then named obesity as one of their core initiatives in 2014. And the goals of this initiative were to make the oncology community more aware of the links between obesity and cancer, to provide tools and resources to providers and patients to start conversations about the role of obesity in cancer, and to help patients start to make healthy lifestyle choices after diagnosis. Another goal of the initiative was to foster a robust research agenda and then finally, as evidence emerges, to ensure access to effective weight management and physical activity programs for cancer patients.

The initiative has had a number of different efforts that it has worked on in the last 18 months. First, about a year ago, we released patient and provider toolkits dealing with weight management and obesity to provide oncology clinicians with some concrete information to provide to their patients about how obesity is linked to cancer and also to give patients some resources in their local communities as well as national resources so they can think about how they could start making healthy lifestyle choices, losing weight, and exercising more after a cancer diagnosis. The next effort that the initiative spearheaded was a policy statement that was released last fall in the Journal of Clinical Oncology that laid out ASCO’s interest in this area and some of the initiatives in terms of awareness, the resources, the research, and policy. And finally, we hosted a summit last fall that was entitled, “Advancing Obesity Clinical Trials in Cancer Survivors” that brought together key stakeholders, both from the science side and the policy side, as well as patients and providers, to think about what the gaps were in our knowledge of how obesity is connected to cancer and to come up with some concrete steps to bridge those gaps and conduct critical research studies that will hopefully determine whether lifestyle intervention programs have a role in the adjuvant care of cancer survivors. Ultimately, we hope that these healthy lifestyle changes will lead to improvements in outcomes for patients with early-stage cancer.

Cancer Network: Just briefly, what do we know about how obesity affects those with a cancer diagnosis? Are there specific tumor types in which obesity is more tightly linked to prognosis?

Dr. Ligibel: The evidence is really strongest at this point in breast cancer, colon cancer, prostate cancer, and some gynecologic cancers. There have been hundreds of observational studies that have looked at the relationship between things like obesity and inactivity and cancer outcomes, especially in breast cancer. And what these studies suggest is that individuals who are obese at the time they are diagnosed with cancer or who are inactive, appear to have a higher risk of cancer recurrence and overall mortality compared with those who are leaner and more physically active. There are also many studies that show that if you take a person who is diagnosed with cancer, who is not exercising and is overweight or obese, and help change their lifestyle, that that will have a number of benefits in terms of their quality of life, their energy, a number of symptoms related to cancer, and side effects of therapy. So, there are concrete benefits that have been demonstrated for lifestyle change after cancer diagnosis. We don’t have a whole lot of direct evidence from randomized trials at this point, but those studies are ongoing for a number of different malignancies and we hope to have much more direct evidence of the impact of these types of programs on cancer outcomes in the next few years.

Cancer Network: Is part of ASCO’s initiative to fund or spearhead studies on this link between obesity and cancer, either in patients who already have cancer or patients who are obese and might develop cancer?

Dr. Ligibel: In the research summit we conducted in the fall, there was a big emphasis on thinking about the funding of these trials. Because these studies are large studies, they have significant expense associated with the conduct of the trial and with the implementation of the lifestyle intervention. And there have not been great mechanisms for ways of bringing together funds for these types of trials. So, that was one of the primary goals of the research summit, to think about what type of infrastructure we need to conduct these trials and how we can bring together the necessary funds. I think that was important as far as key outcomes of that meeting, and we have a paper that was just approved by the ASCO board that we are hoping to have published in the summer or fall that talks about how we can take where we are now in terms of the way research has been conducted and really bring it to the next level, bringing together a lot of stakeholders in this process to make sure we can do the studies that are going to lead to changes in practice.

Cancer Network: What are some of the other future goals for this initiative?

Dr. Ligibel: We are planning another research meeting this fall that will seek to develop new partnerships between ASCO and other organizations that have been working on obesity-related research for many years. We recognize that the connection between obesity and cancer is relatively recent in comparison to the links between obesity and diabetes and obesity and heart disease, so we are working to build partnerships with the Obesity Society, the Endocrine Society, cardiology groups, and other groups who have been actively involved in research, teaching, and advocating for policy changes around obesity. I think that one of the next parts of this initiative is to become more broad-based and to have ASCO play a larger role in conversations about obesity in the United States in general and to think about how we look for solutions for the obesity epidemic and how we can mitigate the effects of obesity on cancer risk and cancer outcomes.

Cancer Network: Thank you so much for joining us today, Dr. Ligibel.

Dr. Ligibel: Thank you.