Partial Breast Irradiation Without Sentinel Lymph Node Biopsy in Low-Risk Early Breast Cancer

NCT07757958 | Not Yet Recruiting Phase 3 DMC

• 1 other identifier: 2026-04-070-001
• Study Type: interventional
• Target: 520
• Locations: 1 country
• Sites: 1

Brief Summary

This is a multicenter, randomized, phase III non-inferiority trial in women aged 40 years or older with clinically node-negative (cN0), pathologically pT1 (≤2 cm), grade 1-2, lymphovascular invasion (LVI)-negative invasive breast cancer treated with breast-conserving surgery (BCS) in whom sentinel lymph node biopsy (SLNB) was omitted (pNx). Eligible patients are randomized 1:1 to partial breast irradiation (PBI) or whole breast irradiation (WBI). The primary aim is to determine whether PBI is non-inferior to WBI with respect to the 5-year recurrence-free survival (RFS) rate. Secondary aims include comparison of axillary recurrence, overall survival, locoregional recurrence, treatment-related toxicity, and quality of life between arms.

Conditions

Breast Cancer; Node-negative Breast Cancer; Early-Stage Invasive Breast Carcinoma

Keywords

Partial breast irradiation; Whole breast irradiation; Breast-conserving surgery; Sentinel lymph node biopsy omission; Node-negative; Radiotherapy de-escalation

Outcome Measures

Primary Outcomes (1)

• 5-Year Recurrence-Free Survival Rate

  Proportion of patients free from a first RFS event at 5 years. An RFS event is defined as the first occurrence of ipsilateral invasive breast recurrence, ipsilateral regional nodal recurrence (including axillary), distant metastasis, or breast cancer death. Measured from date of randomization to first event.

  5 years from randomization

Secondary Outcomes (3)

• 5-Year Axillary Recurrence Rate

  5 years from randomization

• 5-year locoregional recurrence rate

  5 years from randomization

• 5-Year Overall Survival

  5 years from randomization.

Study Arms (2)

Whole Breast Irradiation (WBI)

ACTIVE COMPARATOR

Whole breast irradiation using 3D conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT).

Radiation: Whole Breast Irradiation

Partial Breast Irradiation (PBI)

EXPERIMENTAL

Partial breast irradiation targeting the tumor bed with margin, using 3D-CRT or IMRT, sparing the remainder of the breast.

Radiation: Partial Breast Irradiation

Interventions

Whole Breast Irradiation RADIATION

Total dose 26-45 Gy in 5-20 fractions; each institution applies a pre-selected fractionation schedule consistently. CTV defined per ESTRO guideline to include the whole breast parenchyma; PTV with institutional set-up margin (e.g., 5-7 mm). Tumor bed boost (sequential 10-16 Gy in 4-8 fractions, or simultaneous integrated boost \[SIB\]) per institutional standard. Regional nodal irradiation and high-tangent technique not permitted; axillary levels I-III contoured for dosimetric analysis only.

Whole Breast Irradiation (WBI)

Partial Breast Irradiation RADIATION

Total dose 30-40 Gy in 5-15 fractions. Recommended schedules: 30 Gy in 5 fractions (once daily \[QD\] or twice daily \[BID\]); or 40.05 Gy in 15 fractions (QD over \~3 weeks). Axillary levels I-III contoured for incidental dosimetric analysis only (not a treatment target).

Partial Breast Irradiation (PBI)

Eligibility Criteria

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

You may qualify if:

• Female ≥40 years with histologically confirmed unilateral invasive breast cancer.
• No suspicious nodal metastasis on preoperative axillary ultrasound (cN0).
• Single lesion in the affected breast on preoperative breast ultrasound and mammography.
• Treated with breast-conserving surgery with pathologically negative margins for the invasive tumor.
• Sentinel lymph node biopsy not performed at surgery (pNx).
• Maximum diameter of invasive tumor ≤2 cm on final pathology (pT1).
• Histologic grade 1 or 2.
• Signed informed consent prior to enrollment.

You may not qualify if:

• History of malignancy other than breast cancer within 5 years (except adequately treated non-melanoma skin cancer, or carcinoma in situ excluding breast carcinoma in situ).
• Preoperative diagnosis of carcinoma in situ without axillary nodal sampling, subsequently diagnosed as invasive breast cancer on final pathology with SLNB omitted.
• Lymphovascular invasion present (LVI+).
• Multifocal or multicentric tumor in the same breast confirmed radiologically or pathologically.
• Bilateral or inflammatory breast cancer.
• Prior radiotherapy to the breast or thorax.
• Confirmed pathogenic or likely pathogenic variant in a hereditary breast cancer gene (including BRCA1/2).
• Recurrent breast cancer.

Sponsors & Collaborators

• Samsung Medical Center: lead
• National Institute of Health, Korea: collaborator

Study Sites (1)

Samsung Medical Center

Seoul, 05649, South Korea

Location

MeSH Terms

Conditions

Breast Neoplasms

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Central Study Contacts

Haeyoung Kim

CONTACT

+82234102612; haeyoung0131.kim@samsung.com

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

Model Details: 1:1 randomization to PBI or WBI; non-inferiority design

Study Record Dates

• First Submitted: August 6, 2026
• First Posted: August 11, 2026
• Study Start: August 1, 2026
• Primary Completion (Estimated): June 1, 2036
• Study Completion (Estimated): June 1, 2036
• Last Updated: August 11, 2026

Record last verified: 2026-08

Locations

KR (1)