Can Cutting Calories Treat Breast Cancer? A New Study Looks for an Answer
June 26, 2014
By Nicole Simone, MD, Special to Everyday Health
We know that between 50 and 95 percent of women gain weight during the first year of breast cancer treatment. Why is this? We are not really sure, but many things can contribute.
Patients are under a great deal of stress from the day they receive their diagnosis to the first day of (often daily) treatment to the many follow-up doctors’ visits. The uncertainties of cancer — whether the treatment will work, how fast the cancer will grow, if it will be defeated — add another layer of worry.
Our bodies have good methods to deal with stress in the short term, but researchers think that people who are exposed to a constant level of stress may be more susceptible to weight gain. In addition, some of the treatments we use to fight breast cancer, such as the estrogen-receptor blocker tamoxifen and the steroids used to ease the symptoms of chemo, can also contribute to weight gain.
We also know that women who gain weight after a cancer diagnosis tend to have worse cancer outcomes. They also have more cancer recurrences and lower rates of overall survival compared with women who are able to maintain their weight or decrease it.
These facts taken together, demonstrate the importance of weight and a patient’s metabolism when it comes to cancer incidence and recurrence. In response to these apparent connections, I am currently studying whether adjusting the diet to lower calories will positively impact cancer treatment.
Mice Studies Lead the Way in Calorie Restriction Research
In the Simone laboratory at Thomas Jefferson University here in Philadelphia, we tested the role of decreasing caloric intake in breast cancer. We used models to determine that caloric restriction could:
- Decrease tumor growth in an aggressive breast cancer mouse model
- Make radiation therapy more effective at treating the tumor.
We also wanted to test whether the same would hold true in more aggressive breast cancers, such as those that spread, or metastasize, to other parts of the body. Using a model of one of the most aggressive types, triple negative breast cancer, we found that caloric restriction reduced the number of new tumors, or metastases, in mice. It also took longer for the initial, or primary, tumor to spread, allowing the mice to live longer than mice not on a calorie restricted diet.
How Calorie Restriction May Work to Fight Cancer
Our lab looked at what was happening on cellular and molecular levels to understand how diet could have such a big impact on cancer. We saw that the calorie restriction caused cells surrounding the tumor to stiffen and strengthen, creating a sort of cage around the tumor.
Work from our laboratory and others has shown that calorie restriction changes gene expression across all of the tissues of the body. Some genes are turned on, while others are turned off. Many newer cancer drugs focus on changing the expression of one or several “driver” genes — those that are driving the tumor’s growth and spread. However, since calorie restriction changes the gene expression of a whole array of genes involved in metabolism, it has the potential to the weaken several of the cancer’s lifelines, making the tumor more susceptible to cancer-killing therapies like radiation.
Will Calorie Restriction Work on Humans?
Given our promising results in the lab and a growing understanding of how calorie restriction affects the body, we started a clinical trial called the CaReFOR trial (Caloric Restriction for Oncology Research) to test whether we would observe the same benefits in patients. Enrolled patients develop a personalized plan with a dietician to lower the number of calories they eat, and keep an online diet journal to help stay on track. The patients also receive radiation therapy. If it works, calorie restriction could be a non-toxic way to help fight disease in patients. We are currently enrolling early stage breast cancer patients to the study, and expect preliminary results in 2015.
Nicole Simone, M.D., is a board certified radiation oncologist and an Associate Professor of Radiation Oncology, at Thomas Jefferson University. She is the Breast Cancer Clinical Leader at Jefferson and runs a basic research laboratory that has translated interesting finding directly into the clinic.