Comparison of Tumor Bed Delineation Using a Novel Radiopaque Filament Marker Versus Surgical Clips for Targeting...

Area of Science:

• Oncology
• Radiotherapy
• Surgical Oncology

Background:

• Accurate tumor bed (TB) delineation is critical for effective radiotherapy, particularly for boost doses or partial breast irradiation.
• Standard surgical clip markers (CMs) exhibit significant interobserver variability, impacting treatment precision.
• A novel radiopaque filament marker (FM) was investigated to enhance TB delineation consistency.

Purpose of the Study:

• To evaluate the efficacy of an intraoperatively placed radiopaque filament marker (FM) for tumor bed (TB) delineation.
• To compare the consistency of TB delineation using FM versus traditional surgical clip markers (CMs).
• To assess the impact of FM on radiotherapy targeting accuracy in patients undergoing lumpectomy, with or without oncoplastic reconstruction.

Main Methods:

• An FDA-approved FM was used to outline the TB in patients post-lumpectomy or lumpectomy with oncoplastic reconstruction.
• Patient data from January 2020 to January 2022 were retrospectively analyzed, comparing FM and CM cohorts.
• Six expert radiation oncologists independently delineated TBs, with analyses based on volume variance, dice coefficient, and center of mass (COM) deviation.

Main Results:

• The FM cohort demonstrated significantly lower volume variance (29.7% vs 55.4%) and COM deviation (0.63 cm vs 1.05 cm) compared to the CM cohort.
• Dice coefficients were notably higher for FM (0.54 vs 0.44), indicating superior contour agreement.
• In oncoplastic reconstruction cases, FM showed marked improvements: 21.8% volume variance vs 52.2% and 0.53 cm COM deviation vs 1.25 cm.

Conclusions:

• The radiopaque filament marker (FM) significantly improves tumor bed (TB) delineation consistency over surgical clip markers (CMs).
• FM offers superior accuracy in both standard lumpectomy and complex oncoplastic reconstruction scenarios.
• These findings support the use of FM as a superior tool for precise TB delineation in breast cancer radiotherapy.