Table 1.
American Society for Radiation Oncology (ASTRO) guidelines.
| Characteristic | ASTRO CS grouping | ||
|---|---|---|---|
| Suitable | Cautionary | Unsuitable | |
| Age, y | ≥60 | 50–59 | <50 |
| Tumor size, cm | ≤2 | 2.1–3.0 | >3 |
| T stage | T1 | T0 or T2 | T3-T4 |
| Histology | Invasive ductal or other favorable subtypes | Invasive lobular or DCIS ≤ 3 cm | DCIS > 3 cm |
| ER status | Positive | Negative | NA |
| Grade | Any | NA | NA |
| Margins | Negative (≥2 mm) | Close (<2 mm) | Positive |
| Multifocality, cm | ≤2 | 2.1–3 | >3 |
| Multicentricity | Unicentric | NA | Present |
| LVI | None | Limited/focal | Extensive |
| EIC | None | Yes and tumor size ≤ 3 cm | Yes and tumor size > 3 cm |
| Nodal status | Negative | NA | Positive |
| Nodal surgery | SLNB or ALND | NA | None performed |
| BRCA 1/2 mutation | Not present | NA | Present |
| Neoadjuvant therapy | Not allowed | NA | Used |
CS: consensus statement, DCIS: ductal carcinoma in situ, ER: estrogen receptor, LVI: lymphovascular invasion, EIC: extensive intraductal component, SLNB: sentinel lymph node biopsy, and ALND: axillary lymph node dissection.