Omission of Adjuvant Radiotherapy in Low- and Intermediate-Risk Ductal Carcinoma In Situ After Breast-Conserving Surgery

NCT07762885 | Recruiting Phase 3

• 1 other identifier: FDRT-BC028
• Study Type: interventional
• Target: 636
• Locations: 1 country
• Sites: 1

Brief Summary

This is a prospective, multicenter, randomized, open-label, phase III non-inferiority trial designed to evaluate whether omission of postoperative radiotherapy is clinically acceptable in patients with low- and intermediate-risk ductal carcinoma in situ (DCIS) following breast-conserving surgery. Eligible patients include women aged ≥40 years with ER-positive, low- or intermediate-grade DCIS, tumor size ≤2.5 cm, negative surgical margins ≥3 mm, absence of comedo necrosis, and screen-detected unifocal disease. Patients will be randomized to postoperative observation alone or adjuvant radiotherapy. The primary endpoint is 5-year ipsilateral breast tumor recurrence (IBTR).

Conditions

Ductal Carcinoma In Situ, DCIS

Outcome Measures

Primary Outcomes (1)

• Ipsilateral Breast Tumor Recurrence (IBTR)

  Defined as recurrence of invasive carcinoma or DCIS in the ipsilateral breast.

  5 years

Secondary Outcomes (10)

• Local-Regional Recurrence (LRR)

  5 years

• Breast Cancer-Specific Survival (BCSS)

  5 years

• Overall Survival (OS)

  5 years

• Distant Metastasis-Free Survival (DMFS)

  5 years

• Contralateral Breast Cancer Events

  5 years

Other Outcomes (2)

• Tumor-Infiltrating CD8-Positive T-Cell Density

  Baseline

• Tumor PD-L1 Expression

  Baseline

Study Arms (2)

Radiotherapy Omission

EXPERIMENTAL

Patients will undergo observation alone after breast-conserving surgery and receive standard follow-up and endocrine therapy.

Drug: tamoxifen

Adjuvant Radiotherapy

ACTIVE COMPARATOR

Patients will receive postoperative adjuvant radiotherapy after breast-conserving surgery in addition to endocrine therapy.

Radiation: Adjuvant Radiotherapy; Drug: tamoxifen

Interventions

Adjuvant Radiotherapy RADIATION

One of the following protocol-approved radiotherapy regimens may be delivered: * Partial breast irradiation (PBI): 26 Gy in 5 fractions； * Partial breast irradiation (PBI): 40.05 Gy in 15 fractions. * Whole breast ultrahypofractionated radiotherapy: 26 Gy in 5 fractions； * Moderate hypofractionated whole breast radiotherapy: 40.05 Gy in 15 fractions. Radiotherapy should start within 3 months after surgery.

Adjuvant Radiotherapy

tamoxifen DRUG

Adjuvant endocrine therapy with tamoxifen according to institutional practice.

Adjuvant Radiotherapy; Radiotherapy Omission

Eligibility Criteria

• Age: 40 Years+
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Female patients aged ≥40 years；
• Histologically confirmed low- or intermediate-grade ductal carcinoma in situ (DCIS) without invasive carcinoma, including incidental DCIS identified within benign breast lesions；
• Tumor size ≤2.5 cm on final pathology；
• Negative surgical margins ≥3 mm, including margins obtained after re-excision；
• Estrogen receptor-positive disease (ER ≥10%) with planned endocrine therapy using tamoxifen；
• Unifocal lesion；
• Absence of comedo necrosis；
• Screen-detected disease without bloody nipple discharge or palpable mass；
• Clinically node-negative disease；
• Patients randomized to the radiotherapy arm must initiate radiotherapy within 3 months after surgery；
• Central pathology review by the participating institution required；
• Ability to understand and willingness to sign written informed consent.

You may not qualify if:

• Known BRCA1 or BRCA2 germline mutation carriers (genetic testing not mandatory)；
• Contraindications to radiotherapy, including active connective tissue disease；
• Active infection requiring systemic treatment；
• Bilateral breast cancer or prior contralateral breast cancer；
• Severe uncontrolled comorbidities, including significant cardiac, pulmonary, hepatic, renal, hematologic, or psychiatric disorders；
• History of other malignancies, including thyroid cancer, except adequately treated basal cell carcinoma of the skin or cervical carcinoma in situ；
• Prior thoracic radiotherapy；
• Pregnant or breastfeeding patients；
• Estimated life expectancy ≤5 years；
• Poor compliance or inability to adhere to study follow-up requirements.

Sponsors & Collaborators

• Fudan University: lead

Study Sites (1)

Fudan University Shanghai Cancer Center

Shanghai, 200032, China

RECRUITING

MeSH Terms

Conditions

Carcinoma, Intraductal, Noninfiltrating

Interventions

Radiotherapy, Adjuvant; Tamoxifen

Condition Hierarchy (Ancestors)

Adenocarcinoma; Carcinoma; Neoplasms, Glandular and Epithelial; Neoplasms by Histologic Type; Neoplasms; Breast Carcinoma In Situ; Carcinoma in Situ; Neoplasms, Ductal, Lobular, and Medullary

Intervention Hierarchy (Ancestors)

Combined Modality Therapy; Therapeutics; Radiotherapy; Stilbenes; Benzylidene Compounds; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals

Central Study Contacts

Xiaoli Yu

CONTACT

+86-021-64175590; xiaoliyu@fudan.edu.cn

Jin Meng

CONTACT

+86 18121299532; jinmeng@fudan.edu.cn

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: June 23, 2026
• First Posted: August 13, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): June 1, 2031
• Study Completion (Estimated): June 1, 2036
• Last Updated: August 13, 2026

Record last verified: 2026-06

Locations

CN (1)