A new study published in the March issue of Cancer Epidemiology, Biomarkers and Prevention demonstrates that women who have a recurrence of breast cancer have almost twice as much estrogen in their blood than those without a recurrence despite treatment with anti-estrogen drugs.

estrogen linked to breast cancer recurrenceThe study’s findings point to the possibility that high levels of estrogen contribute to a recurrence of breast cancer in the same fashion as they contribute to the initial development of the disease. “While this makes sense, there have been only a few small studies that have looked at the link between sex hormones in the blood and cancer recurrence,” said Cheryl L. Rock, Ph.D., the lead author of the study. “This is the largest study to date and the only one to have included women taking agents such as tamoxifen to reduce estrogen’s effect on cancer growth” she added.

The study’s results suggest the need for women who have been treated for breast cancer to do as much as they can to reduce the amount of estrogen in their bodies, such as maintaining a high level of regular exercise and keeping the weight down.

Study participants were taken from a larger dietary intervention trial, Women’s Healthy Eating and Living Study (WHEL), which evaluated 3,088 women who were previously treated for early stage breast cancer, but were cancer-free when they entered the study. Participants in WHEL were randomly divided into 2 groups, one eating normal healthy diet as recommended by the FDA guidelines, and the second group following diet high in fruits, vegetables, and fiber. After a seven year follow up, both groups showed the same rate of breast cancer recurrence. Researchers therefore determined that a normal diet following FDA guidelines is adequate.

The current case-control study involved WHEL participants, 153 of whom were cancer-free and 153 with cancer recurrence. Women were matched for body size, age, ethnicity, tumor size and chemotherapy. Researchers analyzed the levels of estradiol and testosterone, both protein-bound and free.

It was determined that increased levels of estradiol, protein-bound and free-circulating, were associated with significantly higher incidence of breast cancer recurrence. It was also found that women with cancer recurrence, had more than twice the amount of estradiol as compared to those who remained cancer-free. No association was found between breast cancer recurrence and the levels of SHBG and testosterone.

The study was funded by The Walton Family Foundation, the National Cancer Institute, and the National Institutes of Health.

Source: American Association for Cancer Research

opinion

  • Given that estrogen has been associated with the development of breast cancer, how surprising is the finding that it may also be linked to the recurrence of breast cancer?
  • What are some other ways of decreasing estrogen levels in the body, besides exercise and weight loss?