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NCT Number: NCT06946238

Single-fraction APBI for Early-stage Breast Cancer With Favorable Histological Subtypes (Breast-1F)

This is a prospective, randomized, monocentric, non-inferiority interventional clinical study comparing an Accelerated Partial Breast Irradiation (APBI) for the surgical bed of early-stage breast cancer patients with favorable histological subtypes, using stereotactic radiotherapy in a single dose of 15.5 Gy with Simultaneous Integrated Boost (SIB) to 21 Gy (study treatment, delivered in a single fraction) versus multifractionated radiotherapy of 30 Gy in 5 fractions (standard treatment, delivered in 5 fractions).

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Key information

Conditions

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

Age range

40 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

About this study

The project refers to a study on patients with early-stage breast cancer with pathological Tumor stage (pT) from in situ (pTis) to pT2 up to 3 cm in diameter, and pathological/clinical nodal stage p/cN0, and favorable histology (Luminal A and Luminal B human epidermal growth factor receptor 2 (HER2)-negative subtypes), comparing an APBI treatment delivered with stereotactic radiotherapy to the Planning Target Volume (PTV) of the tumor bed of the breast with a total dose (TD) of 15.5 Gy in one fraction, with simultaneous integrated boost (SIB) to a TD of 21 Gy to the Gross Tumor Volume (GTV) represented by tumor bed, versus 30 Gy in 5 consecutive fractions to the PTV of the tumor bed, according to the standard APBI protocol of the department (Florence protocol).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Histological diagnosis of breast cancer
  • Patients aged ≥40 years
  • Signed informed consent
  • Stage pTis-T2, up to 3 cm in the greatest diameter
  • Luminal A and Luminal B HER2-negative histological subtypes
  • Negative surgical margins (≥ 0.2 cm)
  • Negative lymph nodes at sentinel lymph node biopsy, or alternatively with imaging tests (Positron Emission Tomography (PET)/Computed Tomography (CT) and/or axillary ultrasound, and/or breast Magnetic Resonance Imaging (MRI) with and without contrast), or, in rare cases, where still performed, with axillary dissection
  • Clinical M0 (PET/CT and/or bone scintigraphy and/or abdomen-pelvis CT with and without contrast in suspected patients), within the previous 3 months.
  • Performance Status (PS) Eastern Cooperative Oncology Group (ECOG) ≤2
  • No prior thoracic radiotherapy
  • Fertile women using contraception methods initiated during oncological treatment.

Exclusion criteria

  • Patients aged < 40 years
  • Tumors > 3 cm
  • Multicentric tumors
  • Positive or close surgical margins (<0.2 cm)
  • Lobular carcinoma
  • Negative hormone receptors
  • HER2-positive
  • BReast CAncer (BRCA) genes BRCA1 and/or BRCA2 positive (only if known)
  • Severe systemic diseases
  • Psychiatric or other disorders that may prevent the patient from signing informed consent
  • Previous invasive cancer, except for skin cancer (excluding melanoma) unless the patient has been disease-free for at least 3 years (e.g., carcinoma in situ of the oral cavity or bladder)
  • Collagen or autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, scleroderma, Sjogren's syndrome)
  • Lymph node disease (N1)
  • Evidence of distant metastasis (M1)
  • Contraindication to systemic treatment
  • Pregnant women
  • Non-compliance with the dose limits established in the treatment plan

Treatment and study plan

Adjuvant single-fraction accelerated partial breast irradiation

Radiation

Experimental arm (arm 1-single-fraction APBI) patients will be treated to a total dose (TD) of 15.5 Gy to the PTV with a simultaneous integrated boost (SIB) to a TD of 21 Gy to the tumor bed, while arm 2-five-fractions APBI patients with 30 Gy/ 5 fractions to PTV.

Other names: Ultrahypofractionated Radiotherapy

Primary outcomes

  1. Ipsilateral Breast Tumor Recurrence (IBTR)

    Time frame: 5 years

    To demonstrate the non-inferiority of local control (ipsilateral breast tumor recurrence - IBTR) of the study treatment (delivered in a single-fraction APBI) compared to the department's standard APBI treatment (delivered in 5 fractions).

Secondary outcomes

  1. Acute toxicity

    Time frame: 1 month

    Acute toxicity grade ≥3 as the maximum toxicity value within 1 month and 3 months after the completion of radiotherapy treatment evaluated with Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC) scale with 4 grades, from 0 no change to 4, worst toxicity

  2. Acute toxicity

    Time frame: 3 months

    Acute toxicity grade ≥3 as the maximum toxicity value within 1 month and 3 months after the completion of radiotherapy treatment evaluated with RTOG/EORTC scale with 4 grades, from 0 no change to 4, worst toxicity

  3. Late toxicity

    Time frame: 5 years

    Late toxicity evaluated with RTOG/EORTC and Common Terminology Criteria for Adverse Events (CTCAE) v5.0 scale, with 5 grades, from 0 = no change, to 5 = death for toxicity

  4. Local Control

    Time frame: 5 years

    Local control of the treated site expressed in terms of local recurrence rate

  5. Local Relapse-Free Survival (LRFS)

    Time frame: From the date of radiotherapy end until the date of local relapse, assessed up to 5 years

    Time to local recurrence

  6. Regional Relapse-Free Survival (RRFS)

    Time frame: From the date of radiotherapy end until the date of regional relapse, assessed up to 5 years

    Time to regional (nodal) recurrence

  7. Distant Metastasis-Free Survival (DMFS)

    Time frame: From the date of radiotherapy end until the date of distant metasis diagnosis, assessed up to 5 years

    Time to distant (metastatic) relapse

  8. Disease-Free Survival (DFS)

    Time frame: From the date of radiotherapy end until the date of first, any ( local, regional, distant) relapse, assessed up to 5 years

    Time to first any relapse: local, regional or distant

  9. Breast Cancer Specific Survival (BCSS)

    Time frame: From the date of radiotherapy end until the date of death from breast cancer, assessed up to 5 years

    Time until death from breast cancer

  10. Overall Survival (OS)

    Time frame: From the date of radiotherapy end until the date of death from any cause, assessed up to 5 years

    Time until death from any cause

  11. Cosmesis

    Time frame: 5 years

    Cosmetic results evaluated with Harvard scale. It assesses the global esthetic appearance of the breast, categorized as Excellent, Good, Fair, or Poor

  12. Acute toxicity interim analysis

    Time frame: 3 months

    An interim analysis of acute toxicity (with RTOG/EORTC andf CTCAE v5.0 scales) will be performed for the first 120 patients

  13. Late toxicity interim analysis

    Time frame: 42 months

    An interim analysis of late toxicity (with RTOG/EORTC andf CTCAE v5.0 scales) will be performed for the first 120 patients

  14. Local relapse interim analysis

    Time frame: 42 months

    An interim analysis of local relapse rate will be performed for the first 120 patients

Other outcomes

  1. Incidence of Treatment-Emergent Adverse Events as assessed with breast tumor specific quality of life questionnaires

    Time frame: 5 years

    Survey with the questionnaire of European Organisation for Research and Treatment of Cancer (EORTC) Quality of life of brain tumor patients (EORTC QLQ BR42) which contains 42 questions on patients' quality of life with answers from 1, lowest grade, to 4, highest grade

  2. Modeling of organ movement

    Time frame: 5 days

    Modeling of organ movement during treatment

  3. Radiomics

    Time frame: 5 years

    Evaluation of radiomic characteristics: Mathematical extraction of the spatial distribution of signal intensities and pixel interrelationships of medical images of the patients, to quantify textural information resampled according to International Biomarker Standardization Initiative (IBSI).

  4. Predictive factors for toxicity, disease progression and death

    Time frame: 5 years

    Identification of clinical, imaging, and laboratory prognostic factors for an aggressive phenotype of Luminal A and Luminal B HER2-negative breast cancer and for toxicity

Study contacts

Contact information is provided by the study sponsor or research team.

Andrei Fodor, MD

CONTACT

[email protected]

+390226437634

Nadia G Di Muzio, Prof

CONTACT

[email protected]

+390226437643

Sponsors and collaborators

Lead sponsor

IRCCS San Raffaele

Other

Registry information

Official study title

Accelerated Partial Breast Irradiation in One Fraction for Patients With Early-stage Disease and Favorable Histological Subtypes (Breast-1F).

Acronym: Breast-1F

Important dates

Study start
2025
Primary completion
2029
Study completion
2035
First posted
Apr 27, 2025
Registry last updated
Dec 4, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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