UMIN-ICDS Clinical Trial

Public title

A Multi-institutional Prospective Observational Study of hypofractionated whole breast radiotherapy with Simultaneous Integrated Boost for Breast conservation surgery

Acronym

SIB-BC Study

Scientific Title

A Multi-institutional Prospective Observational Study of hypofractionated whole breast radiotherapy with Simultaneous Integrated Boost for Breast conservation surgery

Scientific Title:Acronym

SIB-BC Study

Region

Japan

Condition

Breast cancer (after breast-conserving surgery)

Classification by specialty

Radiology

Classification by malignancy

Malignancy

Genomic information

NO

Narrative objectives1

To evaluate the feasibility and safety of hypofractionated whole breast radiotherapy with simultaneous integrated boost (SIB) using intensity-modulated radiotherapy after breast-conserving surgery in routine clinical practice in Japan, and to describe the actual dose-volume parameters.

Basic objectives2

Others

Basic objectives -Others

Feasibility (treatment completion rate)

Trial characteristics_1

Trial characteristics_2

Developmental phase

Primary outcomes

Treatment completion rate, defined as the proportion of all enrolled patients who received all planned radiotherapy fractions without a treatment interruption exceeding five consecutive treatment days for medical reasons (adverse events). Assessed at the end of radiotherapy.

Key secondary outcomes

Acute toxicity: incidence of grade 2 or higher radiation dermatitis from the start to the end of radiotherapy (and unscheduled visits for symptom worsening after completion), graded by CTCAE v5.0.
Late toxicity: incidence of grade 2 or higher breast induration (fibrosis) from 6 months after completion of radiotherapy.
Dose-volume parameters: descriptive statistics for PTV_Breast, PTV_Boost, ipsilateral lung, heart, contralateral breast and skin.
Overall treatment time: number of days from the start to the end of radiotherapy.
Ipsilateral breast tumor recurrence, regional nodal recurrence, distant metastasis, overall survival and progression-free survival.

Study type

Observational

Basic design

Randomization

Randomization unit

Blinding

Control

Stratification

Dynamic allocation

Institution consideration

Blocking

Concealment

No. of arms

Purpose of intervention

Type of intervention

Interventions/Control_1

Interventions/Control_2

Interventions/Control_3

Interventions/Control_4

Interventions/Control_5

Interventions/Control_6

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

18

years-old

<=

Age-upper limit

Not applicable

Gender

Female

Key inclusion criteria

1) Age 18 years or older.
2) Underwent breast-conserving surgery for primary breast cancer (invasive carcinoma or DCIS).
3) Whole breast irradiation plus tumor bed boost is indicated as adjuvant radiotherapy.
4) To receive hypofractionated IMRT with simultaneous integrated boost (SIB).
5) Oral informed consent obtained.

Key exclusion criteria

1) Distant metastasis (stage IV).
2) Previous radiotherapy to the ipsilateral breast or chest.
3) Regional nodal irradiation (supraclavicular, axillary or internal mammary) is planned.
4) Hereditary disorders with radiosensitivity, or active collagen vascular disease (e.g., scleroderma, systemic lupus erythematosus) that contraindicates or poses a high risk for radiotherapy.
5) Pregnant or possibly pregnant.
6) Difficulty in obtaining consent or in evaluation for medical or other reasons.

Target sample size

100

Name of lead principal investigator

1st name	Takeshi
Middle name
Last name	Kodaira

Organization

Aichi Cancer Center Hospital

Division name

Department of Radiation Oncology

Zip code

464-8681

Address

1-1 Kanokoden, Chikusa, Nagoya, Aichi, Japan

TEL

0527626111

Email

109103@aichi-cc.jp

Name of contact person

1st name	Masamune
Middle name
Last name	Noguchi

Organization

Aichi Cancer Center Hospital

Division name

Department of Radiation Oncology

Zip code

464-8681

Address

1-1 Kanokoden, Chikusa, Nagoya, Aichi, Japan

TEL

0527626111

Homepage URL

Email

ma.noguchi@aichi-cc.jp

Institute

Aichi Cancer Center Hospital

Institute

Department

Personal name

Organization

Self funding

Organization

Division

Category of Funding Organization

Self funding

Nationality of Funding Organization

Co-sponsor

Name of secondary funder(s)

Organization

Aichi Cancer Center Hospital Institutional Review Board

Address

1-1 Kanokoden, Chikusa, Nagoya, Aichi, Japan

Tel

0527626111

Email

irb@aich-cc.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

愛知県がんセンター（愛知県）、愛知医科大学（愛知県）、藤田医科大学（愛知県）、三重大学医学部附属病院（三重県）、松任石川中央病院（石川県）

Date of disclosure of the study information

2026

Year

10

Month

06

Day

URL releasing protocol

Publication of results

Unpublished

URL related to results and publications

Number of participants that the trial has enrolled

Results

Results date posted

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

Participant flow

Adverse events

Outcome measures

Plan to share IPD

IPD sharing Plan description

Recruitment status

Enrolling by invitation

Date of protocol fixation

2026

Year

04

Month

07

Day

Date of IRB

2026

Year

04

Month

07

Day

Anticipated trial start date

2026

Year

04

Month

30

Day

Last follow-up date

2030

Year

03

Month

31

Day

Date of closure to data entry

Date trial data considered complete

Date analysis concluded

Other related information

Design: multi-institutional, single-arm, prospective observational study in routine clinical practice at five institutions.

Recruitment: all consecutive patients at each institution who meet all inclusion criteria and none of the exclusion criteria are informed orally by the attending physician and enrolled after oral consent, documented in the medical record. Enrollment runs from the date of institutional permission to March 31, 2029. Each patient is followed until a routine visit between 6 and 12 months after radiotherapy.

Treatment: machine, technique (VMAT, static IMRT) and dose fractionation are not specified and follow each institution's standard practice. Examples in use: whole breast 42.56 Gy / 16 fractions with a simultaneous integrated boost of 50.56 Gy / 16 fractions; 40.05 Gy / 15 fractions with a boost of 48.00 Gy / 15 fractions.

Assessments: before enrollment, at treatment planning, weekly during radiotherapy, at its end, up to 6 months after completion (unscheduled visits), and at the final routine visit 6-12 months after completion.

Variables: age, performance status; tumor site, size, histology, pT, pN, grade, ER/PR/HER2, margin; surgery date and surgical clips; systemic therapy; prescribed dose, technique, image guidance, tumor bed delineation; dose-volume parameters (volume, D95%, D2%, Dmean for PTV_Boost and PTV_Breast; ipsilateral lung V20Gy, V5Gy; heart Dmean; contralateral breast Dmean, Dmax; skin V50Gy, V40Gy); treatment dates, completion, interruptions; adverse events (CTCAE v5.0); recurrence and survival.

Analysis: the primary endpoint is a proportion with all enrolled patients as the denominator; secondary endpoints are descriptive. The sample size of 100 was based on a binomial test (threshold 90.0%, expected 97.5%, one-sided alpha 0.05, power 0.80; 97 required).

Registered date

2026

Year

10

Month

06

Day

Last modified on

2026

Year

10

Month

06

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000072315