National Cancer Survivors Day: Diet and Lifestyle After Breast Cancer

An interview with BCRF researcher Dr. Anne McTiernan

Advances in early detection and treatments have contributed to a nearly 40 percent decline in breast cancer deaths since 1998. As a result of these advances, there are over 3.5 million women and men with a history of breast cancer in the U.S. today, representing the largest group of cancer survivors.

These statistics reflect a promising trend and the progress of research in the last 25 years, but for many women, surviving breast cancer also entails fear and anxiety of a recurrence.

BCRF investigator, Dr. Anne McTiernan is an expert in breast cancer survivorship with a focus on weight control, physical activity, and chemoprevention to prevent new or recurrent breast cancer. In recognition of National Cancer Survivors Day, BCRF spoke with Dr. McTiernan to learn more about how women may reduce their risk of breast cancer recurrence and improve quality of life through lifestyle modifications.

Fat: It’s not just dead weight

BCRF: It is widely recognized that being overweight or obese increases the risk of breast cancer after menopause. Women with breast cancer who are overweight or obese may also have a worse outcome, no matter what their age. What are some reasons for this?

Dr. McTiernan: We think some of this has to do with the changes in hormones from increased fat. Many people may not think of fat as an organ, but it is a very active endocrine organ – meaning that it produces hormones including estrogen and insulin, as well as inflammatory molecules. These are all associated with an increased risk of breast cancer. Our work has shown that when overweight or obese women lose a modest amount of weight (10%), they can reduce the levels of all of these factors. 

This suggests that there are mechanisms to explain the effect of body fatness and breast cancer risk. It also tells us that there are things that women can do. This is important for women with an average risk of breast cancer as well as women at high risk. For those at higher risk, chemoprevention, such as endocrine therapy may also be recommended to prevent recurrence.

Advice for breast cancer prevention holds true for prevention of recurrence.

BCRF: Why are lifestyle choices important after a breast cancer diagnosis? 

Dr. McTiernan: We know from observational studies that having overweight or obesity increases the risk of having a recurrence. We know that modest weight loss has the same effect on hormones and inflammatory markers in women with breast cancer as it does in women without breast cancer.  Not only can losing weight reduce the risk of recurrence, but it can also improve quality of life. This doesn’t mean that lifestyle changes can replace treatment, but it can enhance it by helping women feel better.

BCRF: What are the current recommendations to reduce the risk of a recurrence?

Dr. McTiernan: The American Cancer Society and the American Society for Clinical Oncology released guidelines for cancer patients and survivors, which mirror those for prevention:

• Maintain a healthy weight: If overweight limit consumption of processed foods and beverages high in sugar and/or fat, while increasing physical activity to help reduce weight;
• Stay active: Aim for 150 minutes/week of moderate (like walking) or 75 minutes/week of vigorous (such as running) aerobic activity plus strength training twice a week and resume regular activity as soon as possible;
• Eat well: Consume a diet high in vegetables, whole grains, legumes and low in saturated fat;
• Limit alcohol consumption: We know that alcohol consumption increases the risk of breast cancer, though it is less clear what impact it might have on risk of recurrence.

Patients and survivors should check with their doctors, however, to be sure that these recommendations are safe for them.

BCRF: Do we know that following these recommendations will reduce risk of recurrence?

Dr. McTiernan: We are lacking the randomized clinical trials to show that lifestyle interventions can prevent recurrence, but these trials take years to conduct. A related example I like to use is the recommendation that exercise is good for your heart. There has never been a large scale clinical trial showing that exercise actually reduces the risk of a heart attack, but enough small studies have shown that exercise reduces the biological markers of heart disease risk.

Similarly, there are enough small studies in breast cancer survivors to be able combine the data to obtain similar risk reduction corollaries and potentially follow women longer to be able to quantify them with actual outcomes data. We anxiously await the outcomes from several ongoing clinical trials.

Small steps can have big effects.

BCRF: What do you tell your patients who may find making lifestyle changes difficult during or after treatment?

Dr. McTiernan: We don’t want to add stress to patients’ lives. While they are interested in the long-term prognosis, they are living it day by day. It’s important that they understand modest changes can have a big effect on improving their quality of life. Incorporating exercise into daily routines can be as easy as a walk with a friend or a pet and has many benefits. Clinical trials have shown that exercise can actually reduce the feeling of fatigue, improve mood and sleep, and attenuate some side effects from cancer therapy.

The other thing I do is to advise women not to gain weight. Most women gain one to two pounds a year. Lifestyles changes can prevent that.  

Read more about Dr. McTiernan’s BCRF research on our Meet the Researchers page.