Stage 0 includes: Tis, N0, M0. 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. M0: No clinical or radiographic evidence of distant metastases. Imaging studies are not required to assign the M0 category. (AJCC 8th ed.) [from NCI]