Tamoxifen and the uterus

The Role of Estrogens in BRCA1/2 Mutation Carriers

Persons undergoing genetic testing for an inherited predisposition to cancer often raise questions about recommendations for follow-up care. Missing from current guidelines is consideration of the role of estrogens for BRCA1/BRCA2 mutation carriers. Potential implications of hormones for risk of cancer and effectiveness of risk-reduction strategies need to be considered in the design of comprehensive guidelines for high-risk women. Patients who are mutation carriers may ask questions about the use of oral contraceptives, hormone replacement, and utility of current screening modalities. Controversy exists, even when considering these issues for the general population, but become more imperative when considering young, unaffected women who carry an inherited genetic mutation making decisions that may have long-term health consequences. Many patients have considered estrogen ablation via prophylactic surgeries as risk-reduction interventions. This article reviews data regarding these issues, makes recommendations based on available information, and offers future perspectives for those identified at high risk for cancer because of genetic predisposition. Although questions remain regarding the potential implications of hormones for risk of cancer and effectiveness of risk-reduction strategies, all information should be considered when educating and caring for such patients.

Tamoxifen, screening and new oestrogen receptor modulators

Tamoxifen is a selective oestrogen receptor modulator (SERM) with anti-oestrogenic properties in the breast and oestrogenic effects in tissues such as bone and the cardiovascular system. It is an excellent breast cancer drug for all stages of the disease. Its SERM profile makes it a valuable alternative to hormone replacement therapy, especially for women at high risk of breast cancer. Tamoxifen, however, increases the incidence of benign and malignant lesions of the uterus. Secondary prevention of these, early detection and treatment, is feasible but not cost-effective in breast cancer patients because potential endometrial risks do not outweigh beneficial effects in the breast. This may be different in healthy women with an as yet unknown benefit on breast cancer mortality. We review the literature on the importance of tamoxifen's endometrial lesions and balance available evidence on whether and how best to screen them. In a subset of tamoxifen users it seems advisable to assess the uterine cavity prior to intake with a yearly endometrial assessment as pointed out, starting 3 years after initiation of treatment. In most cases there is endometrial thickening on ultrasonographic assessment and additional tests such as hydrosonography or hysteroscopy are required to confirm an empty atrophic uterus as remains the case in most asymptomatic women on tamoxifen. Newer compounds, such as raloxifene, have a similar SERM profile to tamoxifen but are neutral on the uterus. This has recently been proven by 3 years of endometrial follow-up data. Longer endometrial safety will hopefully confirm these early findings. Whether other SERMs in development are better, and which of them is better for the breast, is to be demonstrated in ongoing studies.

Guidelines for monitoring patients taking tamoxifen treatment

Tamoxifen is the most important anti-breast cancer drug in clinical use and has the potential to be used as a chemopreventive breast cancer agent. Using outpatient hysteroscopy and based on 2 case control and 2 cohort follow-up studies in our department, we were able to demonstrate that 50% of women receiving long term tamoxifen experienced some sort of adverse endometrial effects. Although many women retain an atrophic endometrial layer, tamoxifen intake can lead to extensive senile cystic atrophia of the human endometrium, to endometrial hyperplasia and to endometrial polyp formation. Based on a critical review of the literature, we have shown that tamoxifen doubles the risk for developing endometrial cancer in postmenopausal women, although this increased risk may be higher and is duration (i.e. time of use)-dependent. Screening patients with breast cancer for endometrial abnormalities while they are taking tamoxifen is feasible and uterine morbidity related to tamoxifen intake is preventable. Although screening may increase drug compliance it may not be cost-beneficial. However, uterine safety becomes important when only a small benefit of the treatment is to be expected as in the use of tamoxifen in healthy women for breast cancer prevention. The aim of this report is to discuss methods and guidelines for detecting endometrial adverse effects of tamoxifen and to provide the clinician with a current opinion on timing and frequency of screening patients taking tamoxifen for the development of endometrial cancer. In summary, those who advocate screening should start with pretreatment uterine assessment using transvaginal ultrasonography or outpatient hysteroscopy. Symptom-free women with a normal pretreatment uterine cavity can be screened annually with transvaginal sonography from 2 to 3 years after the start of tamoxifen. Hysteroscopy or saline infusion sonography will be required if there is endometrial thickening because the only value of transvaginal ultrasonography is a normal finding being a thin rectilinear endometrium.