Hormone replacement therapy only increases the risk of breast cancer in some women. The new analysis, published by the Journal of Family Planning and Reproductive Health, challenges the results of a 2003 study that indicated such an association.
The Million Women Study in the UK, which included one million postmenopausal women, unleashed the storm around hormone replacement therapy (HRT). There was consternation among the doctors then, because this therapy was considered completely safe. For fear of breast cancer, many women using HRT have stopped taking the female sex hormones (estrogens or gestagens, or tablets containing both hormones).
HRT was expected to alleviate menopausal symptoms, such as hot flashes, sleep and mood disorders, and decreased sex drive. However, MWS research suggested that estrogen use by 30 percent. increases the risk of breast cancer. Combined therapy involving the use of estrogens and gestagens turned out to be even more risky: it was supposed to double the risk of developing this type of cancer.
The risk was higher the longer HRT was used. However, it was enough to stop the treatment and after 5 years it returned to the same level as in women who have never used hormones.
The Journal of Family Planning and Reproductive Health, however, argues that the conclusions of the Million Women Study are incorrect, as fundamental mistakes were made in the study itself. First of all, it has not been taken into account that some cases of breast cancer may have arisen before the start of the studies and before the participating women started using hormone replacement therapy. It is not possible for the disease to develop within one or two years of the study.
The MWS research shows that among participating women the number of breast cancerous tumors increased by 40%. But no distinction was made as to how large the height of those using HZT was.
So why had no one noticed this before? Prof. Samuel Shapiro of the University of Cape Town in South Africa said the research showed that it was accepted uncritically, without thinking about its methodology. The specialists were impressed by the huge population of women on which they were conducted.
AFP cites letters from the authors of the Million Women Study who cite 20 other studies supporting their finding that HRT increases the risk of breast cancer. It has also been shown that when women started giving up therapy, the incidence of this cancer decreased.
Prof. Richard Peto, an epidemiologist at Oxford University, emphasizes that the so-called hormone-dependent breast cancer is three times more common in women using HRT.
Prof. Anne Gombel, a French specialist who is a member of the International Menopause Society, says that obese women with thick breasts and those who abuse alcohol are most at risk of developing breast cancer.
In her opinion, the risk of hormone replacement therapy must be considered individually, in individual women. Some will mainly benefit from this treatment, but others may be at greater risk of breast cancer.
“In any case, the Million Women Study does not show that hormone replacement therapy increases the risk of breast cancer,” emphasizes the Journal of Family Planning and Reproductive Health.