Table 2.

Interpretation of ASTRO APBI Consensus Guidelines for DCIS and intraoperative radiation therapy

Patient group	Criteria	Treatment recommendation
Suitable	Preoperative • Age ≥50 y • Screen detected • Unifocal • Size ≤2.5 cm • Low to intermediate grade Postoperative • Resected with margins ≥2 mm∗	•No further treatment after BCS/IORT
Cautionary	Preoperative • Age 40-49 y if all other criteria for “suitable” are met • ≥50 y if patient has at least 1 “cautionary” factor and does not have any “unsuitable” factors: • Clinically detected • High-grade • HR negative • Size 2.6-3.0 cm Postoperative • Resected with margins ≥2 mm • Occult HR-positive T1mi/T1 disease	•No further treatment after BCS/IORT
Unsuitable	Preoperative • Age <40 y • Age ≥40 y but has “unsuitable” factors: • Size >3 cm Postoperative • Resected with close (<2 mm) or positive margins • Occult HR-negative T1mi/T1 disease†	•Re-excision lumpectomy and WBI for positive margins •Re-excision lumpectomy discussed for close margins •WBI for HR-negative T1mi/T1 disease

Abbreviations: APBI = accelerated partial breast irradiation; ASTRO = American Society for Radiation Oncology; BCS = breast-conserving surgery; DCIS = ductal carcinoma in situ; HR = hormone receptor; IORT = intraoperative radiation therapy; T1mi/T1 = microinvasive/invasive; WBI = whole breast irradiation.

Based on the 2016 ASTRO APBI Updated Consensus Guidelines.¹⁴

Patient should meet both preoperative and postoperative criteria to remain in a suitability group.

^∗ASTRO guidelines define wide local excision with margin ≥3 mm as suitable.

^†HR-negative T1mi/T1 disease considered unsuitable for IORT alone given higher rate of IBTR observed in the TARGIT-A and ELIOT trials among this patient subset.