1. primary tumor (T) TX primary tumor cannot be determined. T0 No evidence of primary tumor. tis Carcinoma in situ: Tis Catheter carcinoma in situ Tis Lobular carcinoma in situ Tis Papillary Paget’s disease without masses Note: Paget’s disease with masses is classified according to tumor size. T1 Tumor maximum diameter ≤2cmT1mic microinvasive carcinoma, maximum diameter ≤0,1cmT1a Tumor maximum diameter >0,1cm, but ≤0,5cmT1b Tumor maximum diameter >0,5cm, but ≤1cmT1c Tumor maximum diameter >1cm, but ≤2cmT2 Tumor maximum diameter >2cm, but ≤5cmT3 Tumor maximum diameter >5cmT4 Regardless of Tumor size, direct invasion of chest wall or skin T4a Tumor invasion of chest wall, excluding pectoral muscle T4b Breast skin edema (including cellulite), or ulceration, or skin satellite nodes not exceeding ipsilateral breast T4c Both T4a and T4b T4d Inflammatory breast cancer 2, regional lymph nodes (N) NX Regional lymph nodes cannot be identified (e.g., ever removed) N0 Regional lymph nodes without metastasis N1 Ipsilateral axillary lymph node metastasis, mobile N2 Ipsilateral axillary lymph node metastasis, fixed or fused to each other or lack of clinical evidence of ipsilateral axillary lymph node metastasis, but clinical finding* of ipsilateral internal breast lymph node metastasis N2a Ipsilateral axillary lymph node metastasis, fixed or fused to each other N2b Clinical finding* of ipsilateral axillary lymph node metastasis only, without clinical evidence of ipsilateral axillary lymph node metastasis N3 Ipsilateral subclavian lymph node metastasis with or without axillary lymph node metastasis; or clinical evidence of ipsilateral internal mammary lymph node metastasis and axillary lymph node metastasis; or ipsilateral supraclavicular lymph node metastasis with or without axillary or internal mammary lymph node metastasisN3a ipsilateral subclavian lymph node metastasisN3b ipsilateral internal mammary lymph node and axillary lymph node metastasisN3c ipsilateral supraclavicular lymph node metastasis3, distant metastasis (M) Mx distant Metastases could not be assessed M0 No distant metastases M1 With distant metastases 4. Clinical staging Stage 0 TisN0M0I T1N0M0IIA T0N1M0 T1N1M0 T2N0M0IIB T2N1M0 T3N0M0IIIA T0N2M0 T1N2M0 T2N2M0 T3N1,2M0IIIB T4N0M0, T4N1M0 T4N2M0IIIC stage Any T,N3M0IV stage Any T Any N,M1* “Clinically detected” refers to pathological abnormalities on imaging (except lymph node scintigraphy), clinical examination or visualization.