Five Year Risk
A new German study matches the findings of an earlier U.S. study: hormone replacement therapy (HRT) taken for five years increases a woman's risk of contracting breast cancer. The phenomenon is seen only during hormone replacement therapy and the risk drops back down to its normal level five years after the treatment has ended.
The German study involved 3464 breast cancer patients as well as 6657 healthy women aged 50-74 years of age. The women were asked questions about the type of hormone therapy they used if any, which hormones were used, and the length of time for which the women received such therapy.
The study was the fruit of the combined efforts of the German Cancer Research Center (DKFZ) and the University Hospital in Hamburg-Eppendorf, Germany. The study is the direct outcome of the "MARIE" controlled case survey. This important work was funded by the German Cancer Aid (Deutsche Krebshilfe) and took 6 years to complete. The goal of this survey was to discover both the effects of HRT and its associated breast cancer risks.
Earlier HRT Use
Those women who have a history of earlier HRT use have a 37% increase for breast cancer than in those women who are using HRT for the first time. During the therapy, the risk rises to 73% but five years after cessation of treatment, the risk for breast cancer in former HRT users goes down to the levels of women who have never used HRT. Study author Professor Dr. Wilhelm Braendle of Hamburg-Eppendorf University Hospital says that, "These results of the MARIE study confirm findings of two U.S. and U.K. studies (the Women's Health Initiative Study and the Million Women Study) that caused a stir in 2002 and 2003."
Professor Dr. Jenny Chang-Claude of the DKFZ concludes, "It has often been argued that the results of the U.S. study could not be applied to Germany where prescription practices are completely different. Therefore, we captured the various hormone preparations, especially the various progestins, very precisely. We have obtained similar results as the U.S. researchers."
Prof. Chang-Claude believes that the data from this study will give German doctors better information that will lead to a profound effect on their ability to counsel patients on hormone replacement therapy.
One of the major findings in this study was confirmation that the various hormone combinations have different effects on women. In those women who are using HRT for the first time, the combination of estrogen and progestin doubles the risk for breast cancer, while using estrogen alone raises this risk by only 15%, a modest increase. It's important to note that the risk increases in both the combined therapy and the single hormone/estrogen therapy when these preparations are used for longer than five years.
Prof. Braendle explains that the type of HRT therapy influences which type of breast cancer is liable to develop. "The risk of developing one of the less common lobular or tubular breast cancers increases twice as much under HRT as the risk of the common type of ductal carcinoma, which constitutes 40 to 75 percent of all malignant tumors of the breast," says Braendle.