Guiding Sole Intraoperative Radiotherapy in Breast Cancer According to ASTRO Guidelines: Mitigating Adverse Outcomes...

Area of Science:

• Oncology
• Radiation Oncology
• Surgical Oncology

Background:

• Intraoperative radiotherapy (IORT) is a de-escalating adjuvant treatment for low-risk breast cancer.
• Broader criteria previously used in Taiwan led to increased locoregional recurrence (LRR) with sole IORT.
• Revised criteria now align with American Society for Radiation Oncology (ASTRO) eligibility standards for sole IORT.

Purpose of the Study:

• To investigate the impact of aligning sole IORT treatment criteria with ASTRO guidelines on oncological outcomes.
• To compare recurrence rates between ASTRO-suitable and non-suitable patients receiving IORT.
• To evaluate the effectiveness of revised IORT selection criteria in reducing LRR.

Main Methods:

• Retrospective review of 632 invasive breast cancer patients undergoing breast-conserving surgery (September 2014 - March 2022).
• Outcomes assessed for External Beam Radiation Therapy (EBRT), sole IORT, and IORT with supplemental EBRT (IORT+boost).
• Strategic modifications for sole IORT implemented in April 2021 based on ASTRO guidelines.

Main Results:

• ASTRO-suitable patients showed significantly lower LRR (0.00% vs. 10.64%), distant metastasis (0.00% vs. 4.00%), and any recurrence (0.00% vs. 7.79%) compared to non-suitable patients (p < 0.05).
• After adjusting for confounders, sole IORT recipients had higher hazard ratios for LRR than EBRT recipients (overall: 5.79; non-suitable: 5.48).
• The revised ASTRO-aligned criteria demonstrated a significant reduction in recurrence rates.

Conclusions:

• Aligning sole IORT treatment criteria with ASTRO guidelines significantly reduces locoregional recurrence rates.
• These strategic modifications enhance oncological outcomes for invasive breast cancer patients.
• ASTRO guidelines provide a more effective framework for selecting patients for sole IORT.