Dr. Nathan Pennell and Dr. Jennifer Ligibel discuss weight management and physical activity programs for patients with cancer.

TRANSCRIPT:

Hello, and welcome to the ASCO Journal of Oncology Practice podcast. This is Dr. Nate Pennell, medical oncologist at the Cleveland Clinic and consultant editor for the JOP. I'm sure everyone who listens to this podcast is aware that obesity and lack of physical activity are major health problems in the USA, and they contribute to multiple medical conditions such as heart disease, diabetes. But how much do patients and oncologists know about how obesity and lack of physical activity impact cancer incidence or treatment or outcomes? And how do physicians manage these issues in their practice?
With me today to discuss this issue is Dr. Jennifer Ligibel, associate professor at Harvard Medical School and medical oncologist at the Dana-Farber Cancer Institute, where she also serves as director of the Leonard P. Zakim Center for Integrative Therapies and Healthy Living. We'll be discussing her paper, "Oncologists' Attitudes and Practice of Addressing Diet, Physical Activity and Weight Management with Cancer Patients, Findings of an American Society of Clinical Oncology Survey of the Oncology Workforce." Welcome, Dr. Ligibel, and thanks for joining me today.
Thank you so much for having me.
So just to set the stage for our listeners, how big of a problem is obesity and physical inactivity among cancer patients? Is this something that is generally mirroring the larger problem we see in America, or is there anything different about our cancer patients?
Well, we know that obesity and inactivity are risk factors for developing a number of different malignancies. The International Agency for Research in Cancer and the World Cancer Research Fund have both analyzed observational data linking obesity, inactivity, poor dietary quality to the risk of developing malignancy, and have demonstrated really consistent evidence that there is at least 13 different malignancies where obesity, in particular, increases the risk of developing the malignancy. So if you think about the fact that obesity and inactivity are pretty prevalent in the United States, in general, and that these factors also increase the risk of developing malignancy, we find that an even higher proportion of cancer survivors are obese and inactive as compared to the general US population. We also know that treatment that patients get for some malignancies can contribute to weight gain, and also can contribute to inactivity. So you put all of these factors together, and a very large proportion of cancer survivors are at risk for obesity, inactivity, poor dietary quality, or all of those factors together.
I mean, the number that you and your co-authors mention is that almost 1/3 of cancer survivors are obese. That seems like a huge number. So clearly a major problem.
Yes, that's true. And that number has increased significantly over the last decade.
So I know that obesity contributes to cancer risk. But is there data that even treatment of cancer can be impacted by these issues?
Yes. So we know that obesity has an impact on treatment-related outcomes and, likely, on the risk of recurrence and mortality in many different diseases. Breast cancer has been the best studied, where we know that women who are obese when they're diagnosed with breast cancer actually have a 35% higher risk of dying from breast cancer compared to women who are of normal weight when they were diagnosed with breast cancer.
Similar data are emerging in other malignancies. Colorectal cancer, there has been a strong link with obesity and cancer outcomes. Prostate cancer, gynecologic cancers, there's emerging data as well. So we know that these factors can impact the risk of recurrence and mortality. But there's also evidence that suggests that people who have excess adiposity, have metabolic complications of obesity, are at higher risk of complications like poor wound healing after surgery. They're at higher risk of lymphedema and some malignancies. They may be at higher risk of things like peripheral neuropathy related to chemotherapy. So there are a lot of poor outcomes associated with body weight in cancer patients.
Now, I know even dosing of chemotherapy, I believe, obese patients are at risk for under-dosing because people are afraid to give them proper weight-based dosing. So lots of reasons to pay attention to this issue. Is there data, though, that changing that-- intervening with helping patients lose weight or patients at risk losing weight, or increasing their physical activity-- mitigates these risks?
That is a great question, and one that will hopefully be answered within the next few years through a number of large-scale, ongoing phase III trials that are looking at the impact of weight loss, increased physical activity, better dietary quality on cancer recurrence and mortality. We don't have data from randomized trials, at this point, looking at the impact of lifestyle change after diagnosis on outcomes. But we do have a lot of observational data that suggest that individuals who are physically active are at lower risk of recurrence in malignancies like breast cancer, colon, and prostate cancer. And we do also have a lot of information from randomized trials that are smaller in scale that demonstrate that losing weight, exercising more has an impact on shorter-term outcomes, like quality of life, cancer-related and treatment-related side effects like fatigue, neuropathy, joint pain. So we know there are benefits of lifestyle change after cancer diagnosis, but we're still awaiting these large-scale trials that will show us whether changing these behaviors actually reduces the risk of recurrence and mortality.
So already enough evidence that it's important that we address it, but hopefully, we'll have more convincing evidence soon. Can you take us through the ASCO survey? What was the background to doing the survey, and what did it try to assess?
So in 2014, ASCO launched an obesity initiative that really sought to educate the oncology workforce about the connections between obesity and related factors in both cancer risk and outcomes, and to provide tools and resources to help oncologists talk to their patients about physical activity, weight management during and after cancer treatment. There was also a part of the initiative that focused on research and advocacy.
We were interested, given that 2014 was a number of years ago, to look at what were the current attitudes of oncology providers toward these topics? What was their practice? Were they talking about weight? Were they talking about physical activity and diet with their patients?
And what did they perceive as barriers to really implementing behavior change after cancer diagnosis? And so we designed a survey that would be delivered to individuals that were currently seeing oncology patients. And they could be physicians, they could be nurse practitioners, they could be dietitians or anyone that was currently working with oncology patients and was an ASCO member. And then we asked them questions about their practice, about the attention that they paid to these topics, about what they felt got in the way. And then thinking more broadly about how important did oncology providers think that these topics were in the scope of their practice.
Why don't we just jump right into the results? So what were the results from the survey?
So first of all, we found that the people that filled out our survey were pretty typical for the general ASCO membership. So about 2/3 of the people that filled out the survey were based in the US. The other 1/3 were international. We did have a higher proportion of medical oncologists, partly because this was limited to people that were actively seeing patients. We had a nice balance of private practice and academic centers, and we had individuals that were treating all different kinds of cancer. So we were happy with the population that filled the survey out as being fairly representative of oncology providers in the US and more broadly.
We found, when we asked the providers what were their perspectives on issues related to obesity and cancer, that there was a very strong agreement that obesity impacts treatment outcomes in cancer patients. And in fact, more than 90% of the survey respondents strongly agreed or agreed with that statement, which we were very excited to see. There was also high agreement with addressing a patient's weight should be a standard part of cancer care. And most of their respondents felt that it was the responsibility of the treating physician to recommend healthy diet, regular activity, weight management for patients in whom that was relevant.
But there was much less agreement that the oncology workforce felt that they were prepared to be either delivering those interventions or that they had enough information or enough training to really feel comfortable in their skills to help patients start to make these changes. So I thought that was very important that there was high agreement that these things were important, but also a feeling of there needed to be other parts of the health care team that could help patients once these issues were identified in really helping them to make the changes that needed to after diagnosis.
We then asked providers about what they were doing now, and we found that the vast majority of providers that completed the survey indicated that they were asking patients about their physical activity patterns, about their diets. They were assessing patients' weights. And this was both during and after cancer treatment. There was a much lower proportion of survey respondents that were actually making referrals to dietitians, to weight management services for their patients. So although there