Current modalities of accelerated partial breast irradiation

The benefits of adjuvant whole-breast irradiation (WBI) after breast-conserving surgery are well established and WBI is a standard of care. In selected patients with early stage breast cancer, accelerated partial breast irradiation (APBI) has emerged as an alternative treatment option to WBI. Early trials of APBI have demonstrated an excellent local control rate and an associated good-to-excellent cosmetic outcome. APBI can reduce both the treatment volume and overall treatment time of adjuvant radiation therapy, which potentially overcomes logistical barriers associated with WBI that have previously prevented eligible women from pursuing breast-conserving therapy. Likewise, the addition of new modalities for APBI delivery has increased the number of patients who might be eligible for this adjuvant treatment - in the setting of breast-conserving surgery - despite the limited availability of long-term data on APBI outcomes compared to historical WBI outcomes. Ongoing phase III trials aim to compare APBI with WBI and also point the practitioner to the appropriate APBI patient selection criteria. Here, we review available modalities, patient selection criteria and consensus guideline recommendations, and current controversies in APBI.