| Patient factors | Suitable | Cautionary | Unsuitable |
| Age | ≥60 y | 50 - 59 y | <50 y |
| BRCA 1/2 mutation | Not present |
| Present |
| Pathologic factors |
|
|
|
| Tumor size | ≤2 cm* | 2.1 - 3.0 cm | >3 cm |
| T stage | T1 | T0 or T2 | T3-4 |
| Margins | Negative by at least 2 mm | Close (<2 mm) | Positive |
| Grade | Any |
|
|
| LVSI | No** | Limited/focal | Extensive |
| ER status | Positive | Negative |
|
| Multicentricity | Unicentric only |
| Present |
| Multifocality | Clinically unifocal with total size ≤ 2.0 cm‡‡ | Clinically unifocal with total size 2.1 - 3.0 cm‡‡ | If microscopically multifocal > 3 cm in total size or if clinically multifocal |
| Histology | Invasive ductal or other favorable subtypes§ | Invasive lobular |
|
| Pure DCIS | Not allowed | ≤3 cm | If > 3 cm in size |
| EIC | Not allowed | ≤3 cm | If > 3 cm in size |
| Associated LCIS | Allowed |
|
|
| Nodal factors |
|
|
|
| N stage | pN0 (i−, i+) |
| pN1, pN2, pN3 |
| Nodal Surgery | SN Bx or ALNDII II |
| None Performed |
| Treatment Factors |
|
|
|
| Neoadjuvant Therapy | Not allowed |
| If used |