Accelerated Partial Breast Irradiation (APBI): Where Are We Now?

Area of Science:

• Oncology
• Radiation Oncology
• Breast Cancer Treatment

Background:

• Accelerated partial breast irradiation (APBI) is a time-efficient alternative to whole breast irradiation (WBI) in breast conserving therapy.
• APBI techniques include brachytherapy, intraoperative radiation, and external beam radiation therapy (EBRT).
• This review evaluates recent randomized controlled trials (RCTs) on APBI and their clinical implications.

Purpose of the Study:

• To appraise the latest modern randomized controlled trials (RCTs) of accelerated partial breast irradiation (APBI).
• To discuss the application of APBI data to clinical practice.
• To compare APBI outcomes with whole breast irradiation (WBI).

Main Methods:

• Review of recent randomized controlled trials (RCTs) including OCOG-RAPID, NSABP B-39/RTOG 0413, and University of Florence studies.
• Analysis of long-term outcomes, including ipsilateral breast tumor recurrence (IBTR), toxicity, and cosmetic results.
• Evaluation of different APBI delivery techniques (EBRT, brachytherapy) and fractionation schedules.

Main Results:

• The OCOG-RAPID trial showed non-inferiority of APBI to WBI in terms of IBTR (8-year rates: 3% vs. 2.8%), but with worse late toxicity and cosmesis.
• The NSABP B-39 trial, including higher-risk patients, did not demonstrate equivalence, with 10-year IBTR rates of 4.6% for APBI vs. 3.9% for WBI.
• The University of Florence study reported low 10-year local recurrence rates and excellent cosmetic outcomes with a specific EBRT fractionation (30 Gy/5 fractions).

Conclusions:

• APBI integration into practice requires careful patient selection, favoring low-risk ductal carcinoma in situ or early-stage (T1) invasive ductal cancer with favorable characteristics.
• Optimal dose and fractionation for EBRT-based APBI require further research.
• APBI offers improved patient convenience and cost savings compared to WBI when appropriately applied.