Spatially Fractionated Radiotherapy Versus Conventional Radiotherapy in the Treatment of Soft Tissue Sarcoma

Condition(s) studied

Investigational drug(s) / intervention(s)

Spatially Fractionated Radiotherapy: SFRT builds on CRT, administered at 3.0 Gy per fraction for 15-20 fractions, with the addition of weekly high-dose vertices of 8-15 Gy per fraction for 3-4 fractions. It employs Intensity-Modulated Radiation Therapy (IMRT), Intensity-Modulated Proton Therapy (IMPT), or Volumetric Modulated Arc Therapy (VMAT) to create a grid-like pattern of alternating high- and low-dose regions. Target volume delineation includes the gross tumor volume (GTV), clinical target volume (CTV, expanded 0.5-1.0 cm from GTV), and planning target volume (PTV, expanded 1.0 cm from CTV). Prior to each treatment session, cone-beam CT (CBCT) or kilovoltage cone-beam CT (kV-CBCT) is used for Image-Guided Radiation Therapy (IGRT) to verify patient positioning.

Conventional Radiotherapy: CRT is delivered at 3.0 Gy per fraction for a total of 15-20 fractions, utilizing Intensity-Modulated Radiation Therapy (IMRT) or Intensity-Modulated Proton Therapy (IMPT) techniques, ensuring a target volume dose coverage of at least 90%. Target volume delineation includes the gross tumor volume (GTV), clinical target volume (CTV, expanded 0.5-1.0 cm from GTV), and planning target volume (PTV, expanded 1.0 cm from CTV). Prior to each treatment session, cone-beam CT (CBCT) or kilovoltage cone-beam CT (kV-CBCT) is used for Image-Guided Radiation Therapy (IGRT) to verify patient positioning.

Study summary

This study is a multicenter, prospective, randomized controlled phase II clinical trial designed to evaluate the efficacy and safety of Spatially Fractionated Radiation Therapy (SFRT) compared to Conventional Radiation Therapy (CRT) in the treatment of soft tissue sarcoma (STS, minimum tumor diameter ≥5 cm). A total of 106 patients were enrolled and randomized in a 1:1 ratio. The primary endpoint is the objective response rate (ORR) of the target lesion at 3, 6, 9, and 12 months post-radiotherapy, assessed using RECIST 1.1 and Choi criteria. Secondary endpoints include the 1-year local control rate (LC) of the target lesion, progression-free survival (PFS), safety (per CTCAE v5.0), and quality of life (QoL, assessed by EORTC QLQ-C30). CRT is delivered at 3.0 Gy per fraction for a total of 15-20 fractions. SFRT comprises CRT at 3.0 Gy per fraction for 15-20 fractions, augmented by weekly high-dose vertices of 8-15 Gy per fraction for 3-4 fractions, aiming to enhance tumor control and potentially stimulate immune responses.

This study is a multicenter, prospective, randomized controlled phase II clinical trial designed to evaluate the efficacy and safety of Spatially Fractionated Radiation Therapy (SFRT) compared to Conventional Radiation Therapy (CRT) in the treatment of soft tissue sarcoma (STS, minimum tumor diameter ≥5 cm). A total of 106 patients were enrolled and randomized in a 1:1 ratio. The primary endpoint is the objective response rate (ORR) of the target lesion at 3, 6, 9, and 12 months post-radiotherapy, assessed using RECIST 1.1 and Choi criteria. Secondary endpoints include the 1-year local control rate (LC) of the target lesion, progression-free survival (PFS), safety (per CTCAE v5.0). CRT is delivered at 3.0 Gy per fraction for a total of 15-20 fractions. SFRT comprises CRT at 3.0 Gy per fraction for 15-20 fractions, augmented by weekly high-dose vertices of 8-15 Gy per fraction for 3-4 fractions, aiming to enhance tumor control and potentially stimulate immune responses.

Eligibility

Primary outcome measure(s)

• Objective Response Rate (ORR) — 3、6、9、12months
  The objective response rate (ORR) is defined as the proportion of patients with soft tissue sarcoma target lesions achieving complete response (CR) or partial response (PR) at 3, 6, 9, and 12 months post-radiotherapy, evaluated according to RECIST 1.1 and Choi criteria. Per RECIST 1.1, CR is defined as the complete disappearance of all target lesions, and PR is defined as a ≥30% reduction in the sum of the diameters of target lesions. Per Choi criteria, CR is defined as the complete disappearance of all target lesions, and PR is defined as a ≥10% reduction in the sum of the diameters of target lesions or a ≥15% decrease in tumor density (Hounsfield Units, HU) on CT scans.

Trial sites (1)

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