TNM Grading

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Intraductal carcinoma, lobular carcinoma in situ, or Paget's disease of the nipple with no associated invasion of normal breast tissue
  • Tis (DCIS): Ductal carcinoma in situ
  • Tis (LCIS): Lobular carcinoma in situ
  • Tis (Paget's): Paget's disease of the nipple with no tumor. [Note: Paget's disease associated with a tumor is classified according to the size of the tumor.]
• T1: Tumor 2.0 cm or less in greatest dimension
  • T1mic: Microinvasion 0.1 cm or less in greatest dimension
  • T1a: Tumor more than 0.1 but not more than 0.5 cm in greatest dimension
  • T1b: Tumor more than 0.5 cm but not more than 1.0 cm in greatest dimension
  • T1c: Tumor more than 1.0 cm but not more than 2.0 cm in greatest dimension
• T2: Tumor more than 2.0 cm but not more than 5.0 cm in greatest dimension
• T3: Tumor more than 5.0 cm in greatest dimension
• T4: Tumor of any size with direct extension to (a) chest wall or (b) skin, only as described below.
• T4a: Extension to chest wall, not including pectoralis muscle
• T4b: Edema (including peau d'orange) or ulceration of the skin of the breast, or satellite skin nodules confined to the same breast
• T4c: Both T4a and T4b
• T4d: Inflammatory carcinoma.
• Memory Aid for Primary tumor: The two numbers to remember are 2.0 and 5.0
  • T1 is no larger than 2.0 cm
  • T2 > 2.0 - 5.0 cm
  • T3 > 5.0 cm

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed (e.g., previously removed)
• N0: No regional lymph node metastasis
• N1: Metastasis to movable ipsilateral axillary lymph node(s)
• N2: Metastasis to ipsilateral axillary lymph node(s) fixed or matted, or in clinically apparent* ipsilateral internal mammary notes in the absence of clinically evident lymph node metastasis
  • N2a: Metastasis in ipsilateral axillary lymph nodes fixed to one another (matted) or to other structures
  • N2b: Metastasis only in clinically apparent* ipsilateral internal mammary nodes and in the absence of clinically evident axillary lymph node metastasis.
• N3: Metastasis in ipsilateral infraclavicular lymph node(s) with or without axillary lymph node involvement, or in clinically apparent* ipsilateral internal mammary lymph node(s) and in the presence of clinically evident axillary lymph node metastasis; or metastasis in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement
  • N3a: Metastasis in ipsilateral infraclavicular lymph node(s)
  • N3b: Metastasis in ipsilateral internal mammary lymph node(s) and axillary lymph node(s)
  • N3c: Metastasis in ipsilateral supraclavicular lymph node(s)

* [Note: Clinically apparent is defined as detected by imaging studies (excluding lymphoscintigraphy) or by clinical examination or grossly visible pathologically.]

Distant metastasis (M)

• MX: Presence of distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis