After being diagnosed with breast cancer, many women make diet and other lifestyle changes to improve their health as they recover from treatment. Eating a healthy diet that’s rich in fresh, unprocessed foods and low in trans fats after being diagnosed can give you more energy as you recover and improve your quality of life.
Researchers have wondered if eating a low-fat diet after being diagnosed improves survival. A study suggests that postmenopausal women who eat a low-fat diet after a breast cancer diagnosis are less likely to die from breast cancer or any other cause.
The study was published online on June 27, 2017 by the Journal of Clinical Oncology. Read the abstract of “Low-Fat Dietary Pattern and Breast Cancer Mortality in the Women’s Health Initiative Randomized Controlled Trial.”
The research is part of the very large Women’s Health Initiative Clinical Trial and the Women’s Health Initiative Observational Study. Both studies are commonly called the WHI. Together, the two studies include information from more than 161,608 postmenopausal women who were ages 50 to 79 when they joined between 1993 to 1998. The WHI wants to find any links between health, diet, and lifestyle factors and health problems such as cancer.
In this part of the study, called the Women’s Health Initiative Dietary Modification Trial, 48,835 postmenopausal women, ages 50 to 79, who had no history of breast cancer and who ate a diet that was more than 32% fat, were randomly assigned to one of two diet plans:
- 19,541 women were told to eat a low-fat diet (fat intake was supposed to be only 20% of the diet); these women also participated in group sessions led by a nutritionist to teach the women how to reduce their fat intake
- 29,294 women were told to eat their usual diet and received educational materials on healthy eating
The women followed the diet plans for about 8.5 years. The women in both groups did about the same amount of exercise. The women were followed for about 16 years (8.5 years of the study and about 8 more years after the women stopped following the diet plans.
During the 8.5 years of the study, 1,764 women were diagnosed with breast cancer. While fewer women in the low-fat diet group died from breast cancer during this time period (27 deaths in the low-fat diet group compared to 61 deaths in the usual diet group), this difference wasn’t statistically significant, which means that it could be because of chance and not due to the difference in diets.
Still, the number of women who died of any other cause after being diagnosed with breast cancer during the 8.5 years was lower in the low-fat diet group compared to the usual diet group:
- 40 women in the low-fat diet group died of any other cause
- 94 women in the usual diet group died of any other cause
This difference was statistically significant, which means that it was likely due to the difference in diet and not just because of chance.
Overall, during the 16 years of follow-up, fewer women in the low-fat diet group were diagnosed with invasive breast cancer:
- 1,176 women in the low-fat diet group were diagnosed
- 1,854 in the usual diet group were diagnosed
This difference wasn’t statistically significant.
Following the pattern of the first 8.5 years of the study, fewer women in the low-fat diet group died from breast cancer (84 compared to 124) during the 16 years of follow-up. But again, this difference wasn’t statistically significant.
Still, the number of women who died from any other cause after being diagnosed with breast cancer was lower in the low-fat diet group compared to the usual diet group during the 16 years of follow-up:
- 234 women in the low-fat diet group died of any other cause
- 443 women in the usual diet group died of any other cause
This difference also was statistically significant.
Women in the low-fat diet group weighed less than women in the usual diet group.
While these results are encouraging, it’s important to keep several things in mind:
- The study relied on the women accurately reporting what they ate and then estimating the fat content in the food. Sometimes people don’t remember everything they eat or how much of something they eat, which would affect the results of the study.
- The study didn’t look to see if the women stuck to their breast cancer treatment plans completely. Stopping a treatment, such as hormonal therapy, early would affect the study results.
- The study only looked at postmenopausal women diagnosed with breast cancer. The results can’t be applied to premenopausal women with breast cancer.
- While the women in the study had no history of breast cancer, it’s not clear if any of the women had a family history of breast cancer. This could possibly affect the results of the study.
If you’re a postmenopausal woman who’s been diagnosed with breast cancer, it makes sense to make healthy diet and lifestyle choices to keep your risk of recurrence as low as it can be and your overall health the best it can be, including:
- eating a diet low in added sugar and processed foods
- eating a diet rich in unprocessed, nutrient-dense foods (foods that have the most vitamins, minerals, and healthy compounds)
- exercising regularly at the highest intensity level you’re comfortable with
- avoiding alcohol
- not smoking
It also makes sense to stick to your treatment plan. Treatments such as chemotherapy and radiation therapy can require trips to the hospital or doctor’s office for several months. You also may need to take hormonal therapy medicines for 5 or 10 years after surgery. You get the best results when you follow your plan completely and on schedule.
For tips on how to overcome common problems with following a treatment plan, visit the Breastcancer.org Staying on Track With Treatment pages.