S3 guideline: Hormone replacement therapy and cancer risk

Hormone replacement therapy (HRT) is the most efficient treatment for climacteric symptoms and is one of the most frequently prescribed endocrine therapies. Before prescription of any form of HRT, the associated risks and benefits should be weighed up against each other. Potential risks include breast, endometrial, and ovarian cancer. HRT may increase the risk of breast cancer, depending on the duration of treatment and the specific HRT preparation. Combined HRT with estrogens and progestins (EPT) is associated with a higher risk of breast cancer than estrogen-only preparations (ET). Specifically, EPT increases the risk of breast cancer after around 5 years of treatment, whereas ET shows this effect only after longer treatment durations. ET may increase the endometrial cancer risk in postmenopausal women. Non-hysterectomized women should therefore only be treated with EPT of sufficient dosage and duration. Application of EPT for up to 5 years does not increase the endometrial cancer risk. Long-term sequential EPT regimens may increase the endometrial cancer risk. Study results on the use of continually combined EPT for over 5 years are controversial. The association between HRT and ovarian cancer risk is uncertain. However, a recent meta-analysis demonstrated that HRT (ET and EPT) may increase the ovarian cancer risk. Due to the low incidence of this disease, the absolute risk is low. Before the use of any form of HRT, women should be appropriately informed about the abovenamed risks and benefits of this treatment for climacteric symptoms. These risks have to be included in the decision for or against HRT, and have to be reconsidered during the course of long-term use of HRT.