By David Liu, PHD

Sunday Sept 02, 2012 (foodconsumer.org) -- Having a higher estrogen level is a risk factor for breast cancer, a study recently reported in Cancer Causes and Control confirms.  Estrogen, which can be boosted by following a high fat diet and or using hormone replacement therapy, is a known cancer promoter.

A.M. Würtz of Danish Cancer Society Research Center in Copenhagen, Denmark and colleagues found a moderate increase in breast cancer risk in women who had higher estrogens in their blood.  The association was found among both women who had received hormone replacement therapy and those who did not.

But they found no association between SHBG and risk of breast cancer.  SHBG stands for sex hormone-binding globulin, which was found associated with risk of breast cancer in some studies.

Data used for the study came from the prospective Danish population-based 'Diet, Cancer, and Health' cohort.  Among 20,861 postmenopausal women, 348 cases of breast cancer were identified during the follow-up. The cases were compared with the same number of controls to see if there is an association between estrogen and SHBG levels and risk of breast cancer.

The researchers found "Modest direct associations were identified between estrogen levels and breast cancer incidence among both never and baseline HRT users. Estrone and estrone sulfate were more consistently associated among both groups than estradiol. No association was found with SHBG."

They concluded "Despite different hormonal profiles, higher serum estrogen levels were associated with a higher risk of breast cancer among both never and baseline HRT users."

Early studies have suggested that using a low fat diet helps to lower serum estrone levels. But hormone therapy is also an important source for increased levels of serum estrogens.

According to an authoritative report released recently, two things women can do to surely reduce the risk for breast cancer is avoiding medical radiation, which is commonly used in medical diagnostic tools such as mammography and radiotherapy, and hormone replacement therapy, which is used to ease discomfort experienced by women at menopause.

About 230,000 women are expected to be diagnosed with breast cancer each year in the United States and the disease and the complications from the disease and treatment kill nearly 40,000 a year in the country, according to the National Cancer Institute.