Nutritional Alternatives to Tamoxifen
I have read conflicting reports on the benefits vs. the dangers of tamoxifen for breast cancer treatment. Have you found better nutritional alternatives? I have had surgery, chemotherapy and radiation for breast cancer. I’m supposed to take tamoxifen for the next 5 to 10 years, but I'm not comfortable with it.
Why is tamoxifen prescribed to treat breast cancer?
Tamoxifen is a medication known as a selective estrogen receptor modulator, or SERM. Tamoxifen often is prescribed as part of the treatment for ER+ breast cancer. Tamoxifen binds with estrogen receptors, without activating growth in breast cancer cells. In this way, tamoxifen prevents a women’s own estrogen from binding with these cells. As a result, breast cancer cell growth is blocked.
Tamoxifen vs. diet to reduce the risk of breast cancer recurrence
At this time, there are no good research studies that directly compare the use of specific diets or nutritional strategies with the use tamoxifen, to prevent breast cancer recurrence. This means we do not know whether any particular diet or nutritional plan is as effective as tamoxifen for preventing recurrence.
If you decide to try nutrition instead of tamoxifen, you are choosing an approach that is not conclusively proven to reduce risk of recurrence in the same way that tamoxifen can reduce risk. We do know that a healthy diet can reduce risk of recurrence, but we don’t know by how much. For tamoxifen, we know that taking this medication for five years after a breast cancer diagnosis can reduce the risk of recurrence by approximately 50%. We don’t have an exact comparison statistic for diet and nutrition.
Also consider two new studies, called aTTom and ATLAS, which have found that extending the time of taking tamoxifen from 5 years to 10 years after diagnosis can further reduce risk of recurrence by up to 25%. Women who took tamoxifen for 10 years also were significantly less likely to die compared with women taking tamoxifen for only 5 years. In the aTTom and ATLAS trials, the reduced risk of recurrence associated with taking tamoxifen for a full 10 years began after year 7 of taking the medication.
In summary, we know that taking tamoxifen for at least 5 years after diagnosis with ER+ breast cancer, and for up to 10 years after diagnosis, will significantly reduce the risk of breast cancer recurrence and death. Unfortunately, we do not have the same type of research about nutrition and recurrence risk.
Are there nutritional alternatives to tamoxifen?
We do have some research that tells us diet and nutrition have an effect on survival after breast cancer. These studies are not as rigorous as controlled, blinded clinical trials, but they do tell us that nutrition matters. In summary, in addition to taking tamoxifen, making good nutrition choices can reduce recurrence risk.
What do we know about nutrition and breast cancer recurrence?
There have been several large research studies that have tracked what women are eating, and in some cases even assigned women to follow specific diets, and then documented how these dietary factors may affect risk of breast cancer recurrence.
The Women’s Healthy Eating and Living (WHEL) study followed approximately 1,500 women with early stage breast cancer who were treated between 1991 and 2000, and found that women who followed two healthy lifestyle behaviors—eating plenty of vegetables and fruit every day and getting regular physical activity—were nearly 50% less likely to die during the study follow up. This study included women taking tamoxifen and those not taking the medication, so clearly, diet and exercise are important for all women with a history of breast cancer.
Women who ate at least 5 servings of vegetables and fruit per day, and exercised an amount equivalent to at least 30 minutes of brisk walking per day (a minimum of six days per week), benefitted from this reduced risk of death after breast cancer. This is great news, because the health behaviors are very manageable.
You don’t need to become a vegetarian or run marathons to improve your health after breast cancer. Simply eating at least five servings of colorful vegetables and fruit each day, and being physically active—a brisk daily, 30 minute walk at a minimum—is all you need!
Most importantly, both lean and obese women reduced their risk with these healthy lifestyle choices. Even if the obese women did not lose a pound, they still benefitted from eating vegetables and fruit and exercising moderately every day.
Interestingly, doing one or the other of these behaviors did not significantly reduce risk of death after a breast cancer diagnosis. Only the combination of five servings of vegetables and fruit per day and regular physical activity provided measurable health benefits.
Another study, the Women’s Intervention Nutrition Study (WINS), randomly selected 2,437 women with early stage breast cancer to eat a standard healthy diet or to follow a very low-fat diet. The difference in fat intake between the groups was significant: The women in the very low-fat group ate about 33 grams of fat per day, on average. The women in the regular diet group ate about 51 grams of fat per day, on average. The entire group of women was followed for approximately five years.
At the end of this time, the women with estrogen receptor negative (ER-) breast cancer who had been following the low-fat diet were 42% less likely to have had a breast cancer recurrence compared with ER- breast cancer survivors eating the standard, healthy “control” diet. The very low-fat diet did not significantly reduce the risk of breast cancer recurrence among women with a history of ER+ breast cancer.
The women in the very low-fat diet group also lost about six pounds of body weight, on average. Some health experts feel that the weight loss might be the reason that the low-fat diet reduced risk of recurrence among women with ER- breast cancer. Regardless, it does appear that a very low-fat diet may be of particular benefit for women with ER- breast cancer only.
More wise choices on nutrition and lifestyle choices after breast cancer
Other studies have followed large groups of women with a history of breast cancer, tracking what they eat and drink, how much they exercise, and who in the group has a breast cancer recurrence. These studies are observational, and cannot prove cause and effect. Even so, they give us good evidence that what a woman puts in her mouth after a breast cancer diagnosis can help stack the odds in favor of staying healthy, and reducing recurrence risk.
Along with eating vegetables and fruit, exercising regularly, and possibly eating a very low-fat diet if you have a history of ER- breast cancer, the following things may help reduce risk of recurrence:
- Maintaining a healthy body weight. Women with breast cancer, who are obese, have poorer survival than women with breast cancer, who are not obese. However, even if you struggle to lose extra pounds, don’t quit exercising and eating healthfully. As the WHEL study shows, the combination of eating vegetables and fruit and regular physical activity reduces risk of recurrence, even in obese women.
- Limiting or avoiding alcohol. Drinking more than one drink—5 ounces of wine, 12 ounces of beer, or 1.5 ounces of hard liquor— per day appears to increase risk of breast cancer, and its recurrence in women with a history of the disease. Some research even tells us that more than one or two drinks per week may increase risk of breast cancer recurrence. For this reason, if you drink, do not have more than a drink per day, such as a glass of wine or beer with dinner.
- Try a Mediterranean diet. The Mediterranean dietary pattern is associated with a decreased risk of breast cancer. To follow a Mediterranean diet, you need to eat plenty of vegetables, fruit, legumes, olive oil, fish, nuts, seeds, and whole grains.
- Eating soy. Several studies now support that women who regularly eat soy foods have a lower risk of breast cancer and breast cancer recurrence. This is true for both Asian and American women, and for women who ate soy foods early in life and for women who added them into their diet as adults. One study from Korea found that even for women who had a BRCA 1 or 2 mutation, eating soy foods appeared to reduce the risk of breast cancer.
In controlled clinical trials, tamoxifen is proven to reduce the risk of breast cancer recurrence. We do not have this same type of proof for nutrition and diet, but other types of research supports that a healthy diet and lifestyle is very important for regaining and maintaining health after a breast cancer diagnosis.
Please thoroughly discuss the pros and cons of tamoxifen with your oncologist, and obtain additional opinions from other oncologists as well. Get all of the facts about the risks and benefits of tamoxifen and this will allow you to make the best decision for your future health.
Finally, regardless of whether you decide to take tamoxifen, be sure to take care of yourself by making healthy nutrition choices, and getting regular physical activity.
The original question and answer were generously donated by Diana Dyer, MS, RD a cancer survivor, registered dietitian, organic garlic farmer, and the author of "A Dietitian's Cancer Story: Information & Inspiration for Recovery & Healing from a 3-time Cancer Survivor.
Question and Answer updated by Suzanne Dixon, MPH, MS, RD on behalf of the ON DPG
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