Inversely and adaptively planned interstitial brachytherapy: A single implant approach.

Area of Science:

• Radiation Oncology
• Gynecologic Oncology
• Medical Physics

Background:

• Advanced and recurrent gynecologic malignancies pose significant treatment challenges.
• Conventional therapies may have limitations in achieving optimal target coverage and sparing organs at risk.
• Image-based brachytherapy offers precise dose delivery.

Purpose of the Study:

• To assess the efficacy, feasibility, and safety of image-based, inversely and adaptively planned high-dose rate interstitial brachytherapy (HDR-ISBT).
• To evaluate this treatment in a single implant, three-consecutive-day regimen for advanced primary or recurrent gynecologic malignancy.
• To determine survival outcomes and toxicity profiles associated with this HDR-ISBT approach.

Main Methods:

• Retrospective analysis of clinical data from patients treated with HDR-ISBT boost between 2014 and 2017.
• Treatment involved a single implant of interstitial needles (approximately 7 Gy x 4 fractions) over three days.
• CT and MRI imaging were used for inverse and adaptive planning and target delineation.

Main Results:

• Forty women with a median follow-up of 18 months received HDR-ISBT.
• Median target coverage (V100: 98%) and dose (HR-CTV EQD2: 85.1 Gy) were achieved.
• Two-year overall survival, local control, and progression-free survival were 81%, 81%, and 64%, respectively. Grade 3 gastrointestinal toxicity was associated with rectal doses exceeding recommendations.

Conclusions:

• A four-fraction, inversely and adaptively planned, single-implant HDR-ISBT approach is effective for advanced and recurrent gynecologic malignancies.
• This method provides excellent target coverage and local control.
• The treatment demonstrates minimal toxicity when rectal doses are managed within recommended limits.