Stage 0 includes: Tis, N0, M0, G1-3, HER2 Status: Any, ER Status: Any, PR Status: Any. Tis: Ductal carcinoma in situ. Lobular carcinoma in situ is a benign entity and is removed from TNM staging in the AJCC Cancer Staging Manual, 8th Edition. N0: No regional lymph node metastasis is identified or isolated tumor cell clusters (ITCs) are identified only. G1: Low combined histologic grade (favorable); SBR score of 3-5 points. G2: Intermediate combined histologic grade (moderately favorable); SBR score: 6-7 points. G3: High combined histologic grade (unfavorable); SBR score of 8-9 points. M0: No clinical or radiographic evidence of distant metastases. Imaging studies are not required to assign the M0 category. (AJCC 8th ed.) [from NCI]