Breast cancer: not all hormone therapy increases the risk
All content is checked by medical journalists.For many years menopausal women were treated almost across the board by taking female hormones - hormone replacement therapy (HRT). It consists either of a combination therapy with estrogens and progestins or a monotherapy exclusively with estrogens. Since scientists discovered a link between HRT and breast cancer, the therapy has been used much less frequently in the fight against menopausal symptoms. However, not all HRTs may increase the risk of developing breast cancer. Some might even lower it.
"Monotherapy with only estrogens can even reduce the risk of breast cancer," said Dr. Rowan Chlebowski of the Harbor-UCLA Medial Center and colleagues. They had further evaluated the data from a large study by the Women's Health Initiative. The study included a total of over 27,000 women between the ages of 50 and 79 years. Some of them have had breast cancer themselves in the past or have had cases in their families.
Two types of HET
Medical information was requested from women every six months - with the aim of documenting the incidence of breast cancer. Some of the participants received combined HRT with estrogens and so-called progestins, a synthetic form of progestin, for years. The combination with progestin is important for most women as it lowers the risk of certain types of uterine cancer. The remaining participants received HRT with only oestrogens. They had their uterus removed and did not need a progestin.
The number of breast cancers in the two groups was compared with the incidence of breast cancer in placebo groups - that is, with women who had not received hormonal therapy.
Advanced tumors in combination therapy
The result: In the group that received combined HRT, there were more large and advanced tumors than in the placebo group. The scientists suspect that combined HRT makes breast cancer diagnosis by mammography more difficult. It changes the density of the breast tissue. Therefore, the tumors may be discovered later.
Immediately after stopping taking the hormone, the breast cancer risk of women in this group decreased slightly, but later increased again and remained elevated for about ten years.
Estrogens alone do not increase the risk
In contrast, estrogen-only hormone replacement therapy did not increase the risk of breast cancer - there is even evidence that it reduces the risk. The risk was lowest immediately after stopping the intake, after which it slowly rose again to the low starting level.
Unlike a combination therapy, a pure estrogen therapy does not make breast cancer diagnosis difficult, according to the researchers. Early tumor stages could also be better recognized.
Other risks of HRT
Today, hormone replacement therapy is mainly used in women with particularly severe menopausal symptoms. Every woman has to decide for herself whether she wants to accept the long-term risks. In addition to an increased risk of breast cancer, the hormones are also said to increase the risk of cardiovascular diseases and thrombosis.
The new study results give hope that monotherapy with only estrogens at least does not increase the risk of breast cancer. However, there is still a risk of other diseases, such as uterine cancer. (vv)
Source: Chlebowski, R. Breast Cancer After Use of Estrogen Plus Progestin and Estrogen Alone. Analyzes of Data From 2Women’s Health Initiative Randomized Clinical Trials. JAMA Oncol. doi: 10.1001 / jamaoncol.2015.0494
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