Radiotherapy Treatment Planning Comparison Using SBRT-PATHY (Photons) Versus CARBON-PATHY for Unresectable Bulky Tumors

EBG MedAustron GmbH

Overview

This study uses a novel unconventional radiotherapy technique, consisting of high dose PArtial Tumor irradiation targeting exclusively the HYpoxic segment of unresectable bulky tumors delivered either with photons (SBRT-PATHY) or with carbon-ions (CARBON-PATHY) while sparing the peritumoral immune microenvironment (PIM).

This study will be conducted as a two phase study. Phase A is a retrospective study. Up to 10 patients with bulky (\>6cm tumors) previous planned with planning CT with IV contrast will be selected for planning and dosimetry comparison. This is performed to optimize the contouring and planning procedures. Phase B is a prospective study. Ten patients with bulky (\>6cm tumor) requiring radiotherapy, with planning CT and MR with IV contrast will be accrued. Every effort will be made to include equal numbers of patients (2-3) from head and neck, thorax, abdomen and pelvis. Their images will be used for planning and dosimetry comparison. Patients will be treated according to clinical plans. The study plans will not be used for treatment. Treatment plans for Photon delivery (SBRT-PATHY) and Carbon delivery (CARBON-PATHY) to deliver 30 Gy in three fractions will be planned to be delivered to the BTV will be performed. SBRT-PATHY plans will be generated at the Princess Margaret Cancer Center (PMCC, Toronto, Canada) while CARBON-PATHY plans will be generated at the MedAustron Center for Particle Therapy and Research (W. Neustadt, Austria). The objective is to compare the dosimetric profile achievable using SBRT-PATHY (using photons) and CARBON-PATHY (using carbon-ions) for unresectable bulky tumors and surrounding tissues.

Study Type

OBSERVATIONAL

Conditions

Cancer

Interventions

Planning CT, MRIOTHER

SBRT-PATHY and CARBON-PATHY planning is performed for study purposes only. Patients will be treated according to standard radiotherapy as per institutional policies. The planning images (CT, MRI) will be anonymized and used for planning purposes only.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Written informed consent (for use their planning CT and MR data for study specific planning) 2. Malignant solid bulky primary or recurrent tumor with diameter of ≥6 cm 3. Age \> 18 years 4. Radiation planning CT (with IV contrast) and MRI (with or without IV contrast) is planned Exclusion Criteria: 1. Patients without bulky lesions, 2. Contraindication to i.v. CT and MRT contrast medium administration, particularly estimated glomerular filtration rate (GFR) less than 45 mL/min/1.73 m². 3. Female patients who are pregnant, breast-feeding or male or female patients of reproductive potential who are not employing an effective method of birth control, 4. Any condition that, in the opinion of the investigators, would interfere with treatment planning or interpretation of study results Note (1): criterion n°4 will be evaluated on the four eyes principle, evaluated by both Principle Investigator and Sub-Investigators.

Locations (1)

EBG MedAustron GmbH

Wiener Neustadt, Lower Austria, Austria

Outcomes

Primary Outcomes

Phase A: optimization of contouring and planning using PATHY strategy

The objective of phase A is to optimize the target delineation, planning strategy and techniques for SBRT-PATHY at Princess Margaret and CARBON-PATHY at MedAustron.

Time frame: 18 months (phase A and B combined)

Phase B: optimal coverage of Bystander tumor volume (BTV) while allowing the maximal radiation-sparing of PIM and regional lymph nodes

a prospective identification of 10 patients who are recommended to receive radiotherapy fulfilling the inclusion criteria. SBRT-PATHY and CARBON-PATHY planning is perfomed for study purposes only. A planning comparison between SBRT-PATHY (using photons) and CARBON-PATHY (using carbon-ions) based on dosimetric consideration achieved for the targeted BTV, non-targeted surrounding NTV (normoxic tumor segment), PIM, regional metastases (i.e. local regional involved nodes and distant metastases located within 15 cm cranial caudal to GTV), regional uninvolved lymph nodes and surrounding organs at risk (OAR) will be performed.

Time frame: 18 months (phase A and B combined)

Secondary Outcomes

Phase B: Dosimetric-sparing of normoxic tumor volume (NTV)

The normoxic tumor segment (NTV) will be created by subtracting the BTV from the GTV, representing the remaining peripheral tumor segment outside the BTV.

Time frame: 18 months (phase A and B combined)

Phase B: Dosimetric-sparing of Organs at risk (OAR) and regional nodes

The OAR will be delineated on MRT images at the level of the treated area. Particularly normal structures involved by or in the close proximity to the tumor such as vessels, nerves, or hollow organs will be contoured. Contours will be checked and refined on the co-registered simulation CT images.

Time frame: 18 months (phase A and B combined)

Phase B: Feasibility for dosimetric-sparing of regional/distant metastases as abscopal tumor sites (if present)

Data from ClinicalTrials.gov

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