News for week ending 21 June 2002

HORMONES FACTOR IN CANCER RISK FOR OLDER WOMEN

High levels of sex hormones in older women can double their risk of developing breast cancer according to research carried out by Cancer Research UK epidemiologists.

Postmenopausal women with high amounts of oestrogen and testosterone in their blood stream are twice at risk of contracting the disease as those with low levels of hormones, according to the latest study.

Testing for sex hormones may ultimately lead to useful ways of predicting a woman's risk while learning more about the causes of breast cancer and preventing the disease. Since obesity is the biggest known reason for high levels of sex hormones among postmenopausal women, the researchers believe that maintaining a healthy weight could help reduce the danger of older women developing the ailment.

Scientists from Cancer Research's Epidemiology Unit in Oxford, southern England, pooled data from nine separate United Kingdom, United States, Italian and Japanese studies comprising 1,765 healthy women and 663 with breast cancer. In each study, blood samples were taken from postmenopausal women, levels of sex hormones were measured and the patients were monitored for a number of years to see who developed breast cancer.

By combining the results of the nine studies, the researchers were for the first time able to estimate the effect of postmenopausal hormone levels on the risk of breast cancer. For each of the hormones tested, researchers compared one fifth of women with the highest blood level with a fifth of the lowest.

High levels of free estradiol - an active form of oestrogen - more than doubled the risk compared with women who had low levels of the hormone. Those with high testosterone levels were also at more than twice the risk of developing breast cancer.

The study also found that women with raised levels of a molecule called sex hormone binding globulin, which reduces the activity of sex hormones, were at lower-than-usual risk. Women who are obese have low levels of this molecule which probably also helps to raise their risk of the disease.

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