Breast Cancer
Conditions
Keywords
DIBH, regional nodal irradiation, Internal Mammary Irradiation, Robustness Evaluation, Postoperative breast cancer radiotherapy
Brief summary
This study is an investigator-initiated, single-arm, single-center, prospective, observational study. The hypothesis is that during the implementation of deep inspiration breath-hold (DIBH) radiotherapy plans in postoperative breast cancer patients receiving internal mammary irradiation, the actual target dose coverage and organ-at-risk (OARs) dose parameters remain within clinically acceptable ranges.
Detailed description
For patients with left-sided breast cancer, postoperative radiotherapy can expose the heart to excessive radiation, increasing the risk of cardiac toxicity. DIBH displaces the heart away from the chest wall by expanding the thoracic cavity during breath-holding to reduce cardiac radiation doses. Although DIBH has demonstrated efficacy in reducing cardiac exposure in left-sided breast cancer, its application in internal mammary and regional lymph node irradiation remains uncertain due to potential issues related to dose robustness associated with larger target volumes near the heart. The success of DIBH depends on maintaining a stable respiratory gating window; however, individual variations in breath-holding capacity and fatigue may lead to intrafractional and interfractional positional errors, which can compromise target coverage and increase doses to OARs. Surface-guided systems monitor respiratory motion but may not accurately represent the positions of deep-seated targets and OARs, raising concerns about dose coverage, particularly for the internal mammary target. State-of-the art radiotherapy techniques such as Intensity-Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) provide improved dose conformality and reduce high-dose cardiac exposure. However, the integration of these techniques with DIBH and the impact of positional errors on dose robustness remain inadequately studied. Proton therapy, due to its steep dose fall-off, minimizes cardiac and pulmonary exposure but is highly sensitive to positional changes. This sensitivity may amplify uncertainties during DIBH, particularly in the context of internal mammary irradiation. This study aims to evaluate the dose robustness of DIBH in left-sided breast cancer patients undergoing internal mammary irradiation, with a specific focus on the impact of respiratory motion amplitude during breath-holding on dose distribution, as well as intrafractional and interfractional positional errors. Using offline CT and Cone-Beam CT (CBCT) data, it will assess positional deviations and compare the performance of IMRT, VMAT, and Intensity-Modulated Proton Therapy (IMPT) during DIBH. The findings will provide critical evidence to optimize DIBH for internal mammary and regional lymph node irradiation, improving clinical outcomes while minimizing cardiac toxicity.
Interventions
RADIATIONDIBH with 3mm Gating Window
The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ±1.5 mm (3 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via Surface Guided Radiation Therapy（SGRT）systems will be recorded for analysis.
RADIATIONDIBH with 2 mm Gating Window
The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ±1 mm (2 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via SGRT systems will be recorded for analysis.
RADIATIONDIBH with 1.5 mm Gating Window
The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ± 0.75 mm (1.5 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via SGRT systems will be recorded for analysis.
Sponsors
Ruijin Hospital
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
1. Provide a signed and dated informed consent form (ICF) before the initiation of any trial-specific procedures. 2. Female patients aged ≥ 18 years. 3. Histologically confirmed invasive breast cancer. 4. Have received breast-conserving surgery or mastectomy with axillary staging, including sentinel lymph node biopsy and/or axillary lymph node dissection. 5. Able to hold breath for more than 30 seconds after deep inspiration. 6. Planned to receive postoperative radiotherapy targeting regional lymph nodes, including the internal mammary nodes, under DIBH conditions. 7. Planned to undergo moderate hypofractionated radiotherapy. 8. Karnofsky Performance Status (KPS) score ≥ 80. 9. The estimated life expectancy of greater than 5 years . 10. Sufficient wound healing from surgery, with no signs of active infection at the intended radiation site.
Exclusion criteria
1. Pregnant or breastfeeding women. 2. Presence of any severe, uncontrolled comorbidity or medical condition that, in the investigator's judgment, would render the participant unsuitable for the study, compromise protocol compliance, or confound the interpretation of study results. 3. Unable to understand or comply with breath-hold training instructions. 4. Right-sided breast cancer.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Target coverage of the Planning treatment volume (PTV) | Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment. | Target coverage of the PTV, defined by V95% (the percentage of the PTV volume receiving at least 95% of the prescribed dose). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Additional dose-volume parameters of the PTV | Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment. | PTV coverage as measured by V90%, and high-dose volume as measured by V105% and V110%. |
| Dose-volume parameters of the organs at risk (OARs) | Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment. | 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 and V5-V25 for the left lung, and V2 and V4 for the right lung. Serial Organs: Maximum dose for the spinal cord (Dmax), D0.1cc for the left brachial plexus, and D1cc for the esophagus. Other Structures: Mean dose for the left humeral head, contralateral right breast, and thyroid gland. |
| Conformity Index (CI) of the PTV | Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment. | Calculated as V95% / PTV volume. A value closer to 1 indicates better conformity. |
| Homogeneity Index (HI) of the PTV | Upon completion of radiotherapy treatment planning, prior to the first fraction of treatment. | Calculated as (D2% - D98%)/D50%. A lower value indicates better homogeneity. |
| Intra-fractional Error-PTV | During each treatment fraction (daily, approximately 3-4 weeks per patient) | Intra-fractional error is defined as any patient movement occurring during a single radiotherapy fraction, measured by surface-guided or image-guided systems. This outcome evaluates the impact of intra-fractional motion on target coverage using DVH-based metrics. PTV Metrics include: V95%: percentage of PTV receiving ≥95% of prescribed dose, V90%: percentage of PTV receiving ≥90% of prescribed dose, High-dose volume: V105% and V110%, percentage of PTV receiving ≥105% or ≥110% of prescribed dose, HI: (D2% - D98%) / D50%, where D2%, D98%, D50% are doses covering 2%, 98%, and 50% of PTV, CI: (PTV volume covered by prescription dose)² / (PTV volume × prescription isodose volume). |
| Intra-fractional Error-OARs | During each treatment fraction (daily, approximately 3-4 weeks per patient) | Intra-fractional error is defined as any patient movement occurring during a single radiotherapy fraction, measured by surface-guided or image-guided systems. This outcome evaluates the impact of intra-fractional motion on OAR doses using DVH-based metrics. OAR Dose Metrics: Heart and LV: mean dose, D1cc, V2-V30, LAD : D0.1cc, Lungs: mean dose and V5-V25 for left lung, V2 and V4 for right lung, Spinal cord: Dmax, Left brachial plexus: D0.1cc, Esophagus: D1cc, Other relevant structures: mean dose for left humeral head, contralateral breast, thyroid gland, Unit of measurement: Gy for absolute doses; % for volume-based metrics. |
| Inter-fractional Error- PTV | Across all treatment fractions (approximately 3-4 weeks per patient) | Inter-fractional error is defined as positional variation occurring between different treatment days, measured using daily CBCT image registration and dose recalculation. This outcome evaluates the impact of inter-fractional motion on PTV coverage using DVH metrics. PTV Metrics include: V95%: percentage of PTV receiving ≥95% of prescribed dose, V90%: percentage of PTV receiving ≥90% of prescribed dose, High-dose volume: V105% and V110%, percentage of PTV receiving ≥105% or ≥110% of prescribed dose, HI: (D2% - D98%) / D50%, where D2%, D98%, D50% are doses covering 2%, 98%, and 50% of PTV, CI: (PTV volume covered by prescription dose)² / (PTV volume × prescription isodose volume). |
| Inter-fractional Error- OAR | Across all treatment fractions (approximately 3-4 weeks per patient) | Inter-fractional error is defined as positional variation occurring between different treatment days, measured using daily CBCT image registration and dose recalculation. This outcome evaluates the impact of inter-fractional motion on OAR doses using DVH metrics. OAR Dose Metrics: Heart and LV: mean dose, D1cc, V2-V30, LAD : D0.1cc, Lungs: mean dose and V5-V25 for left lung, V2 and V4 for right lung, Spinal cord: Dmax, Left brachial plexus: D0.1cc, Esophagus: D1cc, Other relevant structures: mean dose for left humeral head, contralateral breast, thyroid gland, Unit of measurement: Gy for absolute doses; % for volume-based metrics. |
Countries
China
Contacts
CONTACTLu Cao, PhD
Outcome results
None listed