Oral Tamoxifen vs. TamGel vs. Control in Women With Atypical Hyperplasia or Lobular Carcinoma In Situ

• Status: Recruiting
• Trial end date: 2026-12-31
• Target enrollment: 0
• Participant gender: Female

Summary

The investigators plan to prospectively study breast tissue changes after a short course of Tamoxifen (Tam).

• Phase: Phase 2/Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Amy C. Degnim
• Treatments: Afimoxifene; Hydroxytamoxifen; Tamoxifen

Criteria

Inclusion Criteria:

• Willing to return to enrolling institution for follow-up

• Willing to complete required testing

• Ability to complete questionnaire by themselves or with assistance

• Female (sex that was assigned at birth)

• Ipsilateral intact breast with histology confirmation of atypical ductal or lobular hyperplasia, or LCIS, within the last 12 months, whether surgically excised or not.

• Eastern Cooperative Oncology Group (ECOG) performance status ≤1

• Willingness to agree to use ONE effective form of birth control (abstinence is not an allowed method) prior to study entry and for the duration of study participation, and for 2 months following the last dose of study medications. Effective birth control methods are: copper IUD [intrauterine device], diaphragm/cervical cap/shield, spermicide, contraceptive sponge, condoms. Women of childbearing potential must have a negative pregnancy test within five days before starting study medications. Should a participant become pregnant or suspect she is pregnant while participating in this study; the participant should inform the study physician immediately.

• Willingness to avoid exposing breast skin to natural or artificial sunlight (i.e. tanning beds) for the duration of the study.

• Participants must have acceptable organ and marrow function as defined below within 30 days of randomization: judged by treating physician's evaluation of baseline laboratory data.

• Negative urine pregnancy test, if of childbearing potential. and / or FSH to verify menopausal status.

Exclusion Criteria:

• Clinically suspicious mass/lesions Breast cancer in the past 5 years.

• Prior thromboembolism within last 5 years (history of varicose veins and superficial phlebitis is allowed) Current pregnancy or lactation History of other prior breast cancer-specific therapy within the previous 2 years (chemotherapy, anti-HER2 agents, endocrine agents, everolimus, CDK4-6 inhibitors).

• Cytotoxic chemotherapy for any indication in last 2 years.

• Prior use of SERMS or AIs including tamoxifen, raloxifene, anastrozole, letrozole, or exemestane for prevention or therapy within 5 years.

• Exogenous sex steroid, including oral contraceptive pill use within 1 month prior to research core needle biopsy (CNB).

• Use of vaginally administered estrogens and hormone coated IUD such as Mirena is permitted History of any prior ipsilateral breast radiotherapy. Previous unilateral radiation of the contralateral side is allowed.

• Skin lesions on the breast that disrupt the stratum corneum (eg eczema, ulceration).

• History of endometrial neoplasia

• Current smoker. Cessation for at least 6 weeks

• Current users of potent inhibitors of tamoxifen metabolism. The potent inhibitors of tamoxifen metabolism are: bupropion, cinacalcet, fluoxetine, paroxetine, quinidine.

• Participants may not be receiving any other investigational agents within 90 days of enrollment or during this study.

• History of allergic reactions to tamoxifen.

• Uncontrolled intercurrent illness that in the judgement of the treating physician would make them unsuitable for study participation

• Anticoagulation meds and clinical concern for discontinuing meds for study research biopsy.

• Identification of a clinically suspicious mass on examination.