Obesity has long been known to complicate cancer treatment—and in specific cancers has been associated with worse prognoses. That's what led Heather Greenlee, ND, PhD, Assistant Professor in the Department of Epidemiology at the Mailman School of Public Health at Columbia University, New York, N.Y., and her colleagues to take a closer look at the prevalence of obesity among patients with a history of cancer, as well as how those rates have changed in recent years.
The researchers analyzed rates of obesity from 1997 to 2014 in 538,969 adults in the U.S. between 18 and 85 who were part of the National Health Interview Survey (NHIS) for a study that is now published online ahead of print (JCO DOI: 10.1200/JCO.2016.66.4391). Within the sample, 32,447 patients had survived cancer.
The data show obesity rates were higher for patients with cancer compared to individuals without a history of cancer, and obesity rates also increased quicker among the individuals who had had cancer. Prevalence of obesity had increased from 20.9 percent to 29.5 percent during that period for the individuals who had no history of cancer—and from 22.4 percent to 31.7 percent for the individuals who had had cancer.
The study coauthors explain why these findings are so significant in the paper: “It is well established that obesity can influence other medical conditions such as diabetes, heart disease, hypertension, and hypercholesterolemia, which may affect overall survival. In addition, specific chemotherapy agents have cardiac adverse effects that can be compounded by higher BMI. ... Studies of breast, colon, and prostate cancer showed comorbid conditions increase 5-year all-cause and cancer-specific mortality. Therefore, it is important to consider obesity among cancer survivors not only in relation to cancer outcomes, but also in relation to other comorbid diseases.”
Greenlee, the study's lead author, elaborated on how these findings should influence practice.
1 What is new about these findings that was not previously known about the prevalence of obesity among patients who had survived cancer?
“To our knowledge, this study is the first to use a nationally representative dataset to look at the trends over time. We examine annual data from 1997 to 2014.
“NHIS is a nationally representative dataset, which is an ongoing cross-sectional survey of health status, health care access, and behaviors of the U.S. population. We think that this dataset can provide a largely unbiased estimate of obesity among the sampled population.
“This paper clearly shows that obesity rates have been increasing over time for cancer survivors, that this rate is higher than the rate in the general populations, and that there are specific subgroups where the rates of obesity are the highest.
“Obesity is a growing public health issue. It is on a trajectory to get worse over time. And we need to develop effective programs and interventions to change the course of what is happening at a population level.”
2 What should oncologists and oncology care providers know about the prevalence of obesity rates among their patients with cancer—as well as about the resources that are currently available to patients with cancer to treat, manage, and prevent obesity?
“Obesity among cancer survivors is common, and is a growing problem. There are subgroups of patients who are at particular risk of obesity, which puts the patients at risk for a multitude of chronic health issues. Clinicians need to work with their patients to effectively treat and manage obesity.
“Currently, there are not good insurance reimbursement streams for nutrition, physical activity, weight loss, and weight management programs for cancer survivors. If patients want to engage in these, they largely need to pay out of pocket, which is a huge barrier. We know that simply handing patients a booklet on food, physical activity, and weight goals is not enough to effectively change behaviors. Patients need education, skill building, and support to effectively make lasting changes—most people can't do this on their own.”
3 So what is the next step? Who develops those interventions and how do they get implemented?
“Our research program is examining and testing strategies to prevent and manage obesity in the oncology setting. In my opinion, the main barrier to implementing effective weight management programs is financial resources.
“There is not going to be a ‘one-size-fits-all’ approach to manage obesity among cancer survivors. Survivors need to have options that work with their lives and their learning styles. They also likely need ongoing support. We are testing various methods that use in-person, written, and mobile health formats to understand which formats will work best.”