Blood Hormone Levels Predict Long-Term Breast Cancer Risk

A study has found that a single hormone level was associated with breast cancer risk for at least 16 to 20 years among postmenopausal women not using postmenopausal hormones.

A team of scientist at Brigham and Women’s Hospital (Boston MA, USA) analyzed 796 patients with postmenopausal breast cancer who had not received hormone therapy. They conducted blood hormone tests at two time points: between 1989 and 1990, and between 2000 and 2002. They then matched each patient with two controls who were not diagnosed with breast cancer.

Women with hormone levels in the highest 25% for estradiol, testosterone and dehydroepiandrosterone sulfate (DHEAS) had a 50% to107% greater chance for developing breast cancer compared with women in the lowest 25%. Relative risks for developing breast cancer after blood collections were similar at one to 10 years versus 11 to 20 years and also16 to 20 years.

The scientists also investigated whether these higher hormone levels were more closely linked to hormone receptor- (HR) positive breast cancers and if they predicted risk regardless of tumor aggressiveness. In the first case, they found that elevated levels of estradiol increased a woman’s risk for HR-positive breast cancer. In general, increased hormone levels, except for DHEAS, tracked closely with increased risk for HR-positive breast cancer. Data on HR-negative cancers were inconclusive.

The team confirmed the protective effect of sex hormone-binding globulin (SHBG), which seems to negate the cancer-causing effects of certain hormones. Women in the highest 25% of SHBG levels had a 30% lower risk for breast cancer compared with women in the lowest 25% for SHBG levels.

Xuehong Zhang, MD, an instructor in medicine at Harvard Medical School (Boston, MA, USA) said, "We, and others, are now evaluating if the addition of hormone levels to current risk prediction models can substantially improve our ability to identify high-risk women who would benefit from enhanced screening or chemoprevention. If so, the current data suggest that hormone levels would not need to be measured in the clinic more than once every 10, or possibly 20, years." The study was presented at the 11th Annual International Conference on Frontiers in Cancer Prevention Research, held October 16-19, 2012, in Anaheim (CA, USA).

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Brigham and Women’s Hospital
Harvard Medical School