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OncoMatch/Clinical Trials/NCT05297617

Deescalation of Endocrine Therapy Duration in Women With HR+ HER2- Breast Cancer at Very Low Risk

Is NCT05297617 recruiting? Yes, currently enrolling (May 2026). This Phase 2 trial studies Anti-aromatase inhibitor for breast cancer.

Phase 2RecruitingUNICANCERNCT05297617Data as of May 2026

Treatment: Anti-aromatase inhibitorHormone therapy is recommended for five years in all patients with hormone receptor-positive breast cancer, but there is no consensus on its duration in low-risk tumours and especially in postmenopausal women. Adjuvant endocrine therapy (ET) is associated with substantial side effects and long-term decreased quality of life. Moreover, while it has been shown that ET provides a real benefit in reducing the relapse rate over time, the deterioration in quality of life may also have a negative effect on patient adherence to treatment. It is therefore important to offer treatment to women with low-risk cancer less intensive treatment strategies. If recent trials tested longer durations as compared to 5 years for high-risk cancers, older trials have tested shorter durations. The 5-year duration appeared at that time as the gold standard because of optimal benefit-risk ratios of tamoxifen among high-risk patients. However shorter treatments of 2-3 years were already associated with substantial benefits and may be enough for very low risk patients.

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Extracted eligibility criteria

Cancer type

Breast Carcinoma

Biomarker criteria

Required: ESR1 IHC expression of the estrogen receptor ≥50% (≥50%)

IHC expression of the estrogen receptor and/or progesterone receptor ≥50%

Required: PR (PGR) IHC expression of the progesterone receptor ≥50% (≥50%)

IHC expression of the estrogen receptor and/or progesterone receptor ≥50%

Required: HER2 (ERBB2) HER2 negative according to ASCO criteria in immunohistochemistry and/or genomic analysis (HER2 negativity is defined as IHC 0-1+, or [IHC 2+ and FISH or CISH nonamplified]) (IHC 0-1+, or [IHC 2+ and FISH or CISH nonamplified])

HER2 negative according to ASCO criteria in immunohistochemistry and/or genomic analysis (HER2 negativity is defined as IHC 0-1+, or [IHC 2+ and FISH or CISH nonamplified])

Disease stage

Required: Stage PT1, PT2, PN0

Grade: Grade 1Grade 2

pT1 (tumor ≤20 mm), pN0, Grade 1 or Grade 2 OR pT2 (tumor ≤30 mm) and pN0, Grade 1 or Grade 2

Performance status

ECOG 0–1(Restricted strenuous activity)

Prior therapy

Cannot have received: neo-adjuvant hormone therapy

Patients who received a neo-adjuvant hormone therapy

Cannot have received: neo-adjuvant chemotherapy

Patients who received a neo-adjuvant or adjuvant chemotherapy

Cannot have received: adjuvant chemotherapy

Patients who received a neo-adjuvant or adjuvant chemotherapy

Cannot have received: preoperative medical treatment

Patients who received a preoperative medical treatment

Structured fields extracted by AI. May contain errors — verify against the official protocol.

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