Table 3.

Patient groups by suitability according to the ASTRO Consensus Statement

Risk factors	Suitable	Cautionary	Unsuitable
Age	≥ 50 years	40–49 years if otherwise meets criteria for “suitable” OR ≥ 50 years with at least 1 poor pathologic criteria of: - T2 (up to 3 cm) - Margin < 2mm - Limited LVI - Estrogen receptor negative - Microscopically multifocal given total size including intervening unaffected breast parenchyma is 2.1-3 cm (provided lesion is clinically unifocal on physical exam and imaging) - Invasive lobular histology - Pure DCIS ≤3 cm - EIC ≤3 cm	< 40 years OR 40–49 years with poor pathologic features
Margins	≥ 2 mm	< 2 mm	Positive
T stage	Tis or T1
N stage	pN0 (axillary staging required)		pN1-N3
Pure DCIS	If screen detected, ngrI-II, ≤ 2.5 cm size, margins ≥ 3 mm	≤ 3 cm and not otherwise ‘suitable’	> 3 cm

Tis in situ disease, T1 tumors up to 2 cm in size, pN0 pathologically node negative, ngr nuclear grade, LVI lymph vascular invasion, DCIS ductal carcinoma in situ, EIC extensive intraductal component, pN1-N3 pathologically node positive disease