Tamoxifen has pro-oestrogenic effects on the endometrium and thus is associated with an increased prevalence of:
- endometrial polyps: occurs in ~8-36% of women in treated 8
- endometrial hyperplasia: occurs in ~1-20% of women treated ref
- cystic endometrial atrophy
- endometrial carcinoma
Up to one-half of breast cancer patients who are treated with tamoxifen may develop an endometrial lesion within 6-36 months. Therefore, any patient who develops bleeding while taking tamoxifen requires evaluation.
Tamoxifen is a non-steroidal "anti-estrogen" that binds to the estrogen receptor and is used primarily for adjuvant therapy in breast cancer. However, it can also act as a pro-estrogen agonist in a low estradiol environment. The agonist properties can affect the endometrium, and does, in a high percentage of patients (50%).
Tamoxifen may cause the endometrium to appear thickened, irregular, and cystic. Most patients tend to have a multiplicity of findings.
normal endometrial thickness despite tamoxifen use, i.e. <5 mm (although ~50% of those receiving tamoxifen have been reported to have a thickness of >8 mm 2
- it has also been reported that the degree of endometrial thickening corresponds to the duration of tamoxifen therapy
- subendometrial cysts
- usually larger than in untreated women
- sonohysterography may be useful for their identification
Endometrial thickening and subendometrial cysts, similar to ultrasound.
Treatment and prognosis
Ultrasound screening of asymptomatic patients taking tamoxifen has been shown to be problematic due to a high number of false positives. It is thus not recommended routine ultrasound is performed for screening if a lady on tamoxifen is not experiencing bleeding.
It has been proposed that patients taking tamoxifen who present with vaginal bleeding should go directly to hysteroscopy and endometrial biopsy 7.
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- 5. Hann LE, Gretz EM, Bach AM et-al. Sonohysterography for evaluation of the endometrium in women treated with tamoxifen. AJR Am J Roentgenol. 2001;177 (2): 337-42. AJR Am J Roentgenol (full text) - Pubmed citation
- 6. Williams PL, Laifer-narin SL, Ragavendra N. US of abnormal uterine bleeding. Radiographics. 23 (3): 703-18. doi:10.1148/rg.233025150 - Pubmed citation
- 7. Dreisler E, Poulsen LG, Antonsen SL et-al. EMAS clinical guide: assessment of the endometrium in peri and postmenopausal women. Maturitas. 2013;75 (2): 181-90. doi:10.1016/j.maturitas.2013.03.011 - Pubmed citation
- 8. Ascher SM, Imaoka I, Lage JM. Tamoxifen-induced uterine abnormalities: the role of imaging. Radiology. 2000;214 (1): 29-38. doi:10.1148/radiology.214.1.r00ja4429 - Pubmed citation
- 9. Gupta A, Desai A, Bhatt S. Imaging of the Endometrium: Physiologic Changes and Diseases: Women's Imaging. (2017) Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (7): 2206-2207
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