Issues surrounding nutrition and weight management are significantly more pressing now than they were decades ago when obesity was relatively uncommon.
Adverse health outcomes associated with obesity in patients with cancer and in survivors of cancer are vast, including an increased risk for cancer recurrence in some common malignancies.
Although nutrition and weight management have been linked more strongly to outcomes in some malignancies than in others, there is growing evidence that suggest the significance of this among all cancer survivors.
HemOnc Today spoke with Jennifer Ligibel, MD, assistant professor of medicine at Harvard Medical School and senior physician at Susan F. Smith Center for Women’s Cancers at Dana-Farber Cancer Institute, about the importance of nutrition and weight-management during and after cancer care.
Question: What type of an effect does nutrition have on cancer?
Answer: There are a lot of data in this area, primarily coming from observational studies that looked at weight and nutritional patterns in individuals diagnosed with cancer and then followed people over time to see how different food intake patterns and different weights at diagnosis relate to cancer outcomes. Nutrition in cancer survivors has been studied extensively. For example, there have been numerous studies in colon cancer suggesting that a western diet, a diet with high levels of consumption of red and processed meat and also refined sugars is linked to an increased risk for colon cancer recurrence. In prostate cancer, there have been studies connecting things like lycopene and high fruits and vegetable intake to better outcomes. Again, most of this information comes from population-based cohorts, but consistent evidence suggests that consuming a healthy diet is important in cancer survivors. Two randomized trials have been conducted, both in breast cancer, that looked at the impact of changes in diet after cancer diagnosis on the risk for breast cancer recurrence. One trial looked specifically at lowering fat and the other looked at lowering fat and increasing fruit, vegetable and fiber intake. The study that looked only at lowering fat did suggest that patients may do better if they lowered fat in their diets and lost a little bit of weight. The other study didn’t show any impact on breast cancer outcomes. So, there has been a bit of uncertainty with how to approach diet in breast cancer specifically. These are the only two randomized trials that have looked at how nutritional change after cancer diagnosis can potentially impact a patient’s risk for recurrence.
Q: What effect does weight management have on cancer?
At this point, we do not have a lot data from randomized trials looking at the impact of weight loss or changes in diet or physical activity on cancer recurrence. We do have a lot of information, however, from population-based cohorts that show us that obesity at the time of a cancer diagnosis, especially in breast cancer or prostate cancer, is related to an increased risk for cancer recurrence and cancer-related mortality. We also know that obesity is related to an increased risk for comorbidities, such as diabetes and heart disease. Obesity is additionally associated with things like an increased risk for infection after surgery.
Q: Can the food we eat cause cancer to grow and spread? Conversely, can the food we eat decrease the risk?
A: All of the data we have thus far in this area, except for the two randomized trials in breast cancer, come from these population-based cohorts. We know that people who eat diets that are higher in fat and lower in fruits and vegetables are also different in other ways. They are less likely to exercise and they tend to weigh more. There are other factors that could influence the risk for cancer developing or recurring that may be different in people who have healthier lifestyles, so it is important to be careful about drawing any firm conclusions about particular foods causing or preventing cancer. Most of the research we have suggest that exercising regularly, eating a healthy diet and keeping weight in a healthy range seem to be tied to the best cancer outcomes.
Q: What recent research do you find particularly compelling in this area?
A: We are finally getting to the point where we are starting to be able to ask the questions about whether changing people’s behaviors after cancer diagnosis has an impact on their cancer outcomes. There is an exciting trial being conducted now called the LiVES study, headed by Dave Alpert, MD, and Cynthia Thompson, PhD, RD, of University of Arizona Cancer Center, which is the largest trial ever undertaken to evaluate the role of diet and physical activity in promoting PFS among women previously treated for ovarian cancer. This is a very important study and will provide important information over the next few years. There is another trial being conducted in Canada, the CHALLENGE trial, conducted by Kerry Courneya, PhD, which is looking at the effect of physical activity on colon cancer recurrence. We are also initiating a trial in the spring called the Breast Cancer Weight Loss (BWEL) Trial, which will examine the impact of weight loss on the risk for breast cancer recurrence in women who are overweight or obese at the time of breast cancer diagnosis.
Q: Do we know more today than we did a decade ago on the effect weight and nutrition play on cancer?
A: We do know more, but there are still many unanswered questions. There have been many observational studies showing links between body weight, physical activity and diet and cancer recurrence. Observational data is very important for generating the hypothesis that can later be tested in other trials. Without these data, we would likely not suspect that there was such a strong connection between lifestyle factors and cancer outcomes. We also have more studies looking at how to help patients change lifestyle behaviors after cancer diagnosis. These studies are important as we try to implement healthy lifestyle programs in the setting of cancer clinics and also so that we can test hypothesis about whether making these changes improves cancer outcomes.
Q: What tips can you offer patients on nutrition during or after cancer?
A: In the past, cancer patients have often been told that they would likely lose weight as a result of chemotherapy and other cancer treatments. Patients were also advised to “rest” during chemotherapy. For most cancer survivors, we now recognize that many patients gain weight during treatment rather than lose weight. Eating a healthy diet, exercising as regularly as possible and being mindful of weight gain are increasingly being recognized as important goals for cancer patients during therapy. It is important to remember that some recommendations are cancer and treatment specific. Many of the recommendations that have been developed focus on common cancers like breast, prostate and colon cancer. It is important to note that there are malignancies that have very specific concerns regarding nutrition and weight management during and after cancer, like head and neck cancer, where patients are not able to eat for long periods of their treatment.
Q: What tips can you offer patients on weight management during or after cancer?
A: I tell people the most important thing to do is to stay active. Even when they are tired, there is very good evidence that physical activity can alleviate fatigue. If people can stay active, studies have shown that they are much less likely to gain weight after cancer diagnosis. I tell my patients that even if they feel tired, just try walking around the block and try and keep moderate-intensity exercise, like walking, a part of the daily routine, even through cancer treatment.
Q: Is the discussion on nutrition/weight management part of routine cancer care at your institution and other institutions? If not, should it be?
A: There is some variation in the frequency with which these topics are addressed in oncology clinics. This is one of the reasons why ASCO made cancer and obesity one of its core initiatives in 2014 to increase awareness of the connection between obesity and cancer and to encourage discussions between oncology practitioners and cancer patients. As a part of the ASCO initiative, we developed a tool kit which is available at Cancer.net. There is a patient version and a provider version. The goal of the toolkit was to provide patients with specific information about a healthy lifestyle and what to be thinking about during and after therapy. It was also created to give oncologists a resource to be able to provide their patients with information. We also developed a policy statement through this ASCO initiative to raise awareness amongst oncology professionals about the importance of this topic, which was published last year in Journal of Clinical Oncology. ASCO has been involved in developing a research summit and recommendations regarding research in this area to evaluate the best programs and the most effective ways to help people make these changes.
Q: Do you have any final thoughts for our readers?
A: As the obesity rates have continued to rise, obesity is poised to replace tobacco as the number one preventable cause of cancer-related mortality. We need to address this so that that we do not erase some of the gains that we have made in other areas in the last few years in terms of increasing survival rates in cancer. – by Jennifer Southall
For more information:
Jennifer Ligibel, MD, can be reached at The Dana Farber Cancer Institute, 450 Brookline Ave, Boston, MA 02215.
Disclosure: Ligibel reports no relevant financial disclosures.