Proton vs Photon IMRT Toxicity in Breast Cancer (PPTOX-BC)

Comparative Toxicity of Postoperative Proton Versus Photon Intensity-Modulated Radiotherapy(IMRT) in Breast Cancer: A Multicenter, Prospective, Observational Study

This study aims to compare the differences in acute and long-term toxicities between intensity-modulated proton therapy (IMPT) and intensity-modulated photon radiotherapy (IMRT/VMAT) in postoperative breast cancer patients, with a focus on evaluating their impact on critical organs, including the heart, lungs, skin, esophagus, thyroid, and lymphatic tissues. Eligible patients will be followed for at least one year to assess the incidence and severity of both acute and late toxicities, as well as differences in patient-reported outcomes (PROs), cosmetic outcomes following breast-conserving surgery, and overall quality of life.

Study Overview

• Status: Not yet recruiting
• Conditions: Breast Cancer
• Intervention / Treatment: Radiation: Intensity-modulated photon radiotherapy (IMRT/VMAT); Radiation: Intensity-modulated proton therapy (IMPT)

Detailed Description

Eligible breast cancer patients will receive either 4005 cGy (RBE) in 15 fractions once daily or 4256 cGy (RBE) in 16 fractions once daily, five times per week. The radiation dose will be delivered to the ipsilateral chest wall or whole breast, with or without regional nodal irradiation, including the ipsilateral supraclavicular, infraclavicular, and high-risk axillary lymph node regions, and optionally the internal mammary lymph node regions. The decision to administer a tumor bed boost will be made by the treating physician. The boost may be delivered either sequentially (10-12.5 Gy (RBE) in 4-5 fractions) or concurrently (48-49.5 Gy (RBE) in 15-16 fractions). The treating physician will evaluate clinical indications to determine the necessity of regional nodal irradiation and whether the internal mammary nodes should be included in the regional nodal clinical target volume (CTV). All patients will undergo intensity-modulated radiation therapy (IMRT) or intensity-modulated proton therapy (IMPT).

The primary endpoint is a composite of toxicity events, including grade ≥2 ipsilateral arm lymphedema within one year post-radiotherapy, grade ≥2 lymphopenia within three months post-treatment, or grade ≥1 cardiac toxicity within one year post-treatment. Patients will be followed for at least one year to assess acute and late toxicities, cosmetic outcomes (patient-reported) in those undergoing breast-conserving surgery, and quality of life.

Due to the greater difficulty in enrolling patients for IMPT compared to IMRT, the study employs an unbalanced 2:1 allocation ratio (IMRT : IMPT = 2:1). Based on an alpha level of 0.05, 80% power, a 2:1 allocation ratio, an assumed 11% difference in toxicity rates between conventional radiotherapy and IMPT during and within one year post-treatment, and a 6.4% anticipated loss-to-follow-up rate, the estimated total sample size is 750 patients (500 in the IMRT/VMAT group and 250 in the IMPT group).

• Study Type: Observational
• Enrollment (Estimated): 750

Contacts and Locations

• Study Contact: Name: Lu Cao, PhD; Phone Number: +86-021-64370045; Email: cl11879@rjh.com.cn

Study Locations

• China
  • Shanghai, China, Shanghai 200025
    • Ruijin Hospital, Shanghai Jiaotong University School of Medicine
    • Contact: Lu Cao, PhD; Phone Number: 86-021-64370045; Email: cl11879@rjh.com.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Breast cancer patients aged ≥18 years with histologically confirmed disease and indications for postoperative radiotherapy as determined by the treating physician, who are willing to receive radiotherapy using IMPT or IMRT.

Description

Inclusion Criteria:

1. Female patients aged ≥18 years.
2. Pathological diagnosis of invasive breast cancer or ductal carcinoma in situ.
3. Undergone breast-conserving surgery or total mastectomy, with or without stage I breast reconstruction.
4. For invasive carcinoma, sentinel lymph node biopsy, axillary lymph node sampling, or axillary lymph node dissection was performed.
5. Required postoperative adjuvant radiotherapy.
6. Karnofsky Performance Status (KPS) score ≥ 70.
7. The estimated life expectancy of greater than 5 years .
8. Planned to receive photon intensity-modulated radiotherapy (IMRT) or proton IMRT, with written informed consent obtained.

Exclusion Criteria:

1. Prior history of chest radiotherapy.
2. Severe cardiopulmonary dysfunction or other conditions that contraindicate radiotherapy.
3. Pregnancy or breastfeeding.
4. Concurrent active malignancies.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Intensity-modulated photon radiotherapy (IMRT/VMAT); Participants will receive photon intensity-modulated radiation therapy (IMRT) targeting the whole breast or chest wall, with or without regional lymph node irradiation (including the ipsilateral supraclavicular, infraclavicular, and high-risk axillary lymph node regions, and optionally the internal mammary lymph node regions).	Radiation: Intensity-modulated photon radiotherapy (IMRT/VMAT); Participants will receive photon intensity-modulated radiation therapy (IMRT) targeting the whole breast or chest wall, with or without regional lymph node irradiation (including the ipsilateral supraclavicular, infraclavicular, and high-risk axillary lymph node regions, and optionally the internal mammary lymph node regions). The prescribed dose is either 4005 cGy in 15 fractions once daily, or 4256 cGy in 16 fractions once daily. For patients undergoing breast-conserving surgery with high-risk features, the decision to deliver a tumor bed boost will be determined by the treating clinician. The tumor bed boost may be administered either sequentially (10-12.5 Gy in 4-5 fractions) or concurrently (48-49.5 Gy in 15-16 fractions). The attending physician will assess clinical indications to determine the need for regional lymph node irradiation and whether to include the internal mammary lymph nodes within the clinical target volume (CTV) of the regional nodal field.
Intensity-modulated proton therapy (IMPT); Participants will receive photon Intensity-modulated proton therapy (IMPT) targeting the whole breast or chest wall, with or without regional lymph node irradiation (including the ipsilateral supraclavicular, infraclavicular, and high-risk axillary lymph node regions, and optionally the internal mammary lymph node regions).	Radiation: Intensity-modulated proton therapy (IMPT); Participants will receive photon Intensity-modulated proton therapy (IMPT) targeting the whole breast or chest wall, with or without regional lymph node irradiation (including the ipsilateral supraclavicular, infraclavicular, and high-risk axillary lymph node regions, and optionally the internal mammary lymph node regions). The prescribed dose is either 4005 cGy (RBE) in 15 fractions once daily, or 4256 cGy (RBE) in 16 fractions once daily. For patients undergoing breast-conserving surgery with high-risk features, the decision to deliver a tumor bed boost will be determined by the treating clinician. The tumor bed boost may be administered either sequentially (10-12.5 Gy (RBE) in 4-5 fractions) or concurrently (48-49.5 Gy (RBE) in 15-16 fractions). The attending physician will assess clinical indications to determine the need for regional lymph node irradiation and whether to include the internal mammary lymph nodes within the clinical target volume (CTV) of the regional nodal field.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Composite Toxicity Event	Definition: The composite toxicity endpoint is a binary outcome (yes/no), defined as the occurrence of at least one of the following events from the start of radiotherapy up to 1 year post-treatment: Event A (Lymphedema): Development of ≥ Grade 2 upper limb lymphedema;Event B (Lymphopenia): Development of ≥ Grade 2 lymphopenia within 3 months after completion of treatment;Event C (Cardiotoxicity): Development of ≥ Grade 1 cardiotoxicity within 1 year post-treatment. All assessed according to CTCAE v5.0.This primary outcome measure will report the proportion (%) of subjects who experience at least one composite toxicity event.	1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Health-Related Quality of Life (HRQoL)	Assessed using the breast cancer specific EORTC QLQ-C30 (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30) questionnaires. This is a 30-item questionnaire assessing functional scales (physical, role, emotional, cognitive, social functioning) and symptom scales. Scores range from 0 to 100. For functional scales, higher scores indicate better quality of life; for symptom scales, higher scores indicate worse symptoms.	3, 6, 12, 24, 60 months
Acute Radiation-Induced Cardiac Toxicity (RTOG/EORTC)	The incidence and grade of acute radiation-induced cardiac morbidities (e.g., EKG changes or pericardial abnormalities) will be assessed using the Radiation Therapy Oncology Group (RTOG)/European Organisation for Research and Treatment of Cancer (EORTC) Acute Radiation Morbidity Scoring Criteria. Assessments will be conducted weekly during treatment, and at 4 weeks and 3 months post-treatment.	3 months
Acute Radiation-Induced Non-Cardiac Toxicity (CTCAE v5.0)	The incidence and severity of other acute toxicities will be graded using CTCAE v5.0, including fatigue , malaise, radiation dermatitis, and esophageal pain，Esophagitis，Breast infection，pneumonia，Cough and blood system disorder. Assessments will follow the same schedule as above.	3 months
Chronic Radiation-Induced Skin and Cardiac Toxicity (RTOG/EORTC)	The incidence and grade of chronic radiation-induced Other skin and cardiac toxicities will be assessed at 6 and 12 months post-treatment using the RTOG/EORTC Late Radiation Morbidity Scoring Criteria. Specific assessments include: Chronic radiation dermatitis (Late skin toxicity) and Chronic cardiac injury (e.g., pericardial effusion, constrictive pericarditis, cardiomyopathy)	1 year
Chronic Radiation-Induced Toxicity - Multi-System (CTCAE v5.0)	The incidence and severity of chronic radiation-induced toxicities will be assessed at 6 and 12 months post-treatment completion. Evaluations will employ the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0, assessing the following specific adverse events: chest wall necrosis (soft tissue necrosis)；hyperpigmentation ；hypopigmentation；radiation pneumonitis (lung toxicity)；breast atrophy；nipple deformity；breast infection；hyperparathyroidism；hyperthyroidism；lib fracture, brachial plexopathy and joint range of motion decreased.	1 year
Late Radiation-Induced Breast Toxicity (LENT-SOMA)	The incidence and severity of late radiation-induced breast toxicities will be assessed at 6 and 12 months post-treatment using the Late Effects of Normal Tissue-Subjective, Objective, Management, Analytic (LENT-SOMA) scoring system. Specific assessments include: Telangiectasia;Fibrosis; breast/chest edema; ulceration and arm lymphedema.	1 year
Breast Cosmetic Outcome	Assessed via patient self-assessment and physician photographic review using the Harvard/NSABP/RTOG Breast Cosmesis Grading Scale. This scale rates cosmetic outcome on a 4-point scale: Excellent, Good, Fair, or Poor, where higher grades indicate worse cosmetic outcomes.	1 year
Patient-Reported Outcomes (PROs)	Assessed using the PRO-CTCAE (Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events). This is a patient-reported outcome measurement system developed by the National Cancer Institute to evaluate symptomatic adverse events in cancer clinical trials. Each symptom is rated on a 5-point scale ranging from 0 to 4, where higher scores indicate worse symptoms (0=None, 1=Mild, 2=Moderate, 3=Severe, 4=Very severe).	3, 6, 12, 18, 24, 36,48, 60 months
Dose-volume parameters of the Planning treatment volume (PTV)	Target coverage of the PTV, defined by V95% (the percentage of the PTV receiving at least 95% of the prescribed dose).PTV coverage as measured by V90%, and high-dose volume as measured by V105% and V110%.	Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment.
Dose-volume parameters of the organs at risk (OARs)	The dose-volume histograms (DVHs) of OARs will be analyzed. The evaluation will cover:Cardiac Structures: Mean dose, D1cc, and V2-V30 for the heart and left ventricle (LV), along with D0.1cc for the left anterior descending artery (LAD).Lungs: Mean dose, D0.1cc, and V5-V25 for the ipsilateral lung, and V2 and V4 for the contralateral lung.Serial Organs: Maximum dose for the spinal cord (Dmax), D0.1cc for the ipsilateral brachial plexus, and D1cc for the esophagus. Other Structures: Contralateral breast, and thyroid gland.	From CT simulation through completion of all treatment fractions (approximately 4 weeks per patient)
Health-Related Quality of Life (HRQoL)	Assessed using the breast cancer specific EORTC QLQ-BR 23 questionnaire. This is a 23-item breast cancer specific module assessing functional scales(body image, sexual functioning, sexual enjoyment, future perspective) and symptom scales (systemic therapy side effects, breast symptoms, arm symptoms, upset by hair loss). Scores range from 0 to 100. For functional scales, higher scores indicate better functioning; for symptom scales, higher scores indicate worse symptoms.	3, 6, 12, 24, 60 months

Collaborators and Investigators

• Sponsor: Ruijin Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: April 6, 2026
• First Submitted That Met QC Criteria: April 13, 2026
• First Posted (Actual): April 17, 2026

Study Record Updates

• Last Update Posted (Actual): April 17, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Breast Cancer; Intensity-modulated radiation therapy; Toxicity profile; Intensity-modulated proton therapy
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms
• Other Study ID Numbers: RJBC-PPTOX-BC; PPTOX-BC (Other Identifier: RuijinH)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No