A 42-year-old nulliparous woman comes to the office for a follow-up visit. The patient was recently diagnosed with stage I breast cancer that was estrogen receptor positive, HER2 negative, lymph node negative, and without metastases. She underwent a mastectomy and recently completed adjuvant chemotherapy. She has had no weight loss, loss of appetite, weakness, or abdominal pain. The patient also has a history of hypertension controlled with a single medication. She had a normal Pap test 5 years ago, and human papillomavirus co-testing was negative. All previous Pap tests were normal. The patient uses a copper-containing intrauterine device for contraception and has regular menstrual periods that last 5 days with moderate bleeding on the first day. She does not use tobacco, alcohol, or illicit drugs. Temperature is 37.2 C (99 F), blood pressure is 130/80 mm Hg, and pulse is 76/min. BMI is 28 kg/m². Cardiac examination reveals a normal rate and rhythm with no rubs or murmurs. The lungs are clear to auscultation bilaterally. Breast examination is consistent with postmastectomy changes. Because of the estrogen receptor-positive tumor, she will be started on a course of tamoxifen as part of her treatment. Which of the following is the best screening strategy for the side effects of tamoxifen in this patient?

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Explanation: 11ec2b69_bee2_3a10_8f63_eb36c2eb8346_MD0005_00 Tamoxifen is a selective estrogen receptor modulator that is used as an adjuvant therapy in patients with nonmetastatic, estrogen receptor-positive breast cancer and for breast cancer prevention in high-risk women (eg, atypical hyperplasia, age >35 with history of lobular carcinoma in situ). Tamoxifen acts as an estrogen receptor agonist in the endometrium and is associated with an increased risk of endometrial hyperplasia/cancer and uterine sarcoma in postmenopausal women. In premenopausal women, tamoxifen is associated with endometrial polyp development, a typically benign cause of abnormal uterine bleeding. In asymptomatic women taking tamoxifen (such as this patient), regular screening has no proven benefit in detecting endometrial cancer or uterine sarcoma. Therefore, patients on tamoxifen require evaluation only if symptoms develop (eg, abnormal uterine bleeding, postmenopausal bleeding). endometrial polyp (Choice A) An endometrial biopsy is the first step in the evaluation of postmenopausal bleeding, to exclude malignancy. Screening asymptomatic patients on tamoxifen has been shown to increase procedure rates (eg, dilation and curettage) but not increase cancer-detection rates. endometrial biopsy (Choice B) Hysteroscopy, a procedure used to visualize and biopsy the endometrial cavity, is indicated in the evaluation of abnormal uterine bleeding in premenopausal women on tamoxifen. (Choice C) An MRI of the pelvis further evaluates a suspicious uterine mass detected on ultrasound and can be used to assess for metastatic disease; it is not used for uterine sarcoma or endometrial cancer screening. Patients with uterine sarcoma typically have abnormal or postmenopausal bleeding, pelvic pain or pressure, and a palpable uterine mass. (Choice D) Screening patients on tamoxifen for endometrial cancer with an annual transvaginal ultrasound results in high false-positive rates as tamoxifen increases endometrial thickness. Further diagnostic evaluation of such findings is unnecessary as the thickened endometrial tissue is typically benign and resolves after tamoxifen cessation. Educational objective: Tamoxifen, a selective estrogen receptor modulator, increases the risk for endometrial hyperplasia/cancer and uterine sarcoma in postmenopausal women. However, asymptomatic patients on tamoxifen do not require routine screening for these complications. Evaluation via ultrasound or endometrial biopsy is indicated only for symptomatic patients. References: Committee Opinion No. 601: tamoxifen and uterine cancer. (http://www.ncbi.nlm.nih.gov/pubmed/24848920) Surveillance of endometrial pathologies, especially for endometrial cancer, of breast cancer patients under tamoxifen treatment. (http://www.ncbi.nlm.nih.gov/pubmed/19761121)

A 42-Year-Old Nulliparous Woman Comes to the Office for a Follow-Up