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CMECNE

Tamoxifen Therapy and Uterine Cancer Risk: The Data and Clinical Implications

Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Discuss the research findings from studies that have assessed the risk of uterine cancer and tamoxifen
2. Explain the role of routine monitoring for uterine cancer in women who are using tamoxifen

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires faculty, planners, and others in control of educational content to disclose all their financial relationships with ineligible companies. All identified conflicts of interest (COI) are thoroughly vetted and mitigated according to PIM policy. PIM is committed to providing its learners with high quality accredited continuing education activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of an ineligible company.

The PIM planners and others have nothing to disclose. The OBG Project planners and others have nothing to disclose.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from 12/01/2022 through 12/01/2024, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the test and evaluation. Upon registering and successfully completing the test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Designated for 0.2 contact hours of pharmacotherapy credit for Advance Practice Registered Nurses.

Read Disclaimer & Fine Print

SUMMARY:

Tamoxifen, a well known SERM, is used to treat breast cancer (hormone receptor positive) because of well-documented benefits including improved disease-free survival (5-year was 38% higher than placebo) and overall survival, regardless of menopausal status. It also is used as a chemoprophylactic agent for women at high risk for breast cancer. ACOG reaffirmed their guidance on tamoxifen monitoring (2019), which includes a statement that tamoxifen use may be extended to 10 years.

Tamoxifen for Breast Cancer Treatment

Uterine Cancer Risk (NSABBP)

Within first 5 years of follow up
- Average annual hazard rate of endometrial cancer: 1.2/1000 patient-years
- Cumulative hazard rate: 6.3/1000
Endometrial cancers following tamoxifen therapy are not of a different type, nor do they carry worse prognosis
Authors conclude “net benefit greatly outweighs risk”

Tamoxifen for Breast Cancer Risk Reduction

Uterine Cancer Risk (IBIS-I trial) – 96 month follow-up

Endometrial cancer incidence rate
- Tamoxifen group: 0.59/1000 woman-years
- Placebo group: 0.38/1000 woman-years
Majority FIGO state 1, diagnosed in women >50 years

KEY POINTS:

Screening with Transvaginal (TV) Ultrasound
- Tamoxifen results in subepithelial stromal hypertrophy and therefore makes TV ultrasound screening more difficult and less reliable
- Routine TV ultrasound and endometrial biopsy for surveillance have “not shown to be effective”
  - May lead to additional unnecessary procedures and is not recommended
- However, these modalities, including sonohysterography, can be used for follow-up depending on the clinical scenario, especially bleeding
- Counsel and encourage patients to report any bleeding, spotting, leukorrhea or unusual vaginal discharge
Work-up prior to beginning tamoxifen
- Due to increased risk for polyps, screening and managing uterine polyps prior to tamoxifen initiation can reduce the incidence of atypical hyperplasia
- The use of progestins to reduce risk for endometrial hyperplasia is not recommended
- ACOG states that prior to beginning tamoxifen

…there may be a role for pretreatment screening of postmenopausal women with transvaginal ultrasonography, and sonohysterography when needed, or office hysteroscopy

Monitoring
- Postmenopausal
  - Monitor closely “for symptoms of endometrial hyperplasia or cancer”
- Premenopausal
  - Data does not demonstrate increased risk
  - Routine gyn care
If atypical hyperplasia is identified prior to beginning tamoxifen, the patient should be counseled and hysterectomy “should be considered”
- If endometrial carcinoma occurs and is subsequently managed with hysterectomy, “tamoxifen use may be reinstituted” following consultation with the patient’s breast cancer oncology team

Learn More – Primary Sources:

Endometrial cancer in tamoxifen-treated breast cancer patients: findings from the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-14

Long-Term Results of Tamoxifen Prophylaxis for Breast Cancer—96-Month Follow-up of the Randomized IBIS-I Trial

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