Breast

General

Staging



Last author update: 31 March 2022
Last staff update: 31 March 2022

Copyright: 2002-2022, PathologyOutlines.com, Inc.

PubMed Search: Staging[title] breast carcinoma[title]

Emily S. Reisenbichler, M.D.
Debra L. Zynger, M.D.
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Cite this page: Reisenbichler ES, Zynger D. Staging. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastmalignantstaging.html. Accessed December 3rd, 2022.
Definition / general
  • All carcinomas of the breast are covered by this staging system
  • Breast sarcomas, phyllodes tumor and breast lymphomas are not staged using this system
Essential features
  • AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
ICD coding
  • ICD-10:
    • C50.0 - nipple
    • C50.1 - central portion of breast
    • C50.2 - upper inner quadrant
    • C50.3 - lower inner quadrant
    • C50.4 - upper outer quadrant
    • C50.5 - lower outer quadrant
    • C50.6 - axillary tail
    • C50.8 - overlapping lesion of breast
    • C50.9 - breast, not otherwise specified
Primary tumor (pT)
  • pTX: cannot be assessed
  • pT0: no evidence of primary tumor
  • pTis: ductal carcinoma in situ, Padget disease, encapsulated papillary carcinoma and solid papillary carcinoma
    • pTis (DCIS): ductal carcinoma in situ without invasive carcinoma
    • pTis (Paget): Paget disease without invasive carcinoma
  • pT1mi: tumor ≤ 1 mm
  • pT1a: tumor > 1 mm but ≤ 5 mm
  • pT1b: tumor > 5 mm but ≤ 10 mm
  • pT1c: tumor > 10 mm but ≤ 20 mm
  • pT2: tumor > 20 mm but ≤ 50 mm
  • pT3: tumor > 50 mm
  • pT4a: extension to chest wall (not including pectoralis muscle)
  • pT4b: edema (including peau d'orange), ulceration of skin or ipsilateral satellite skin nodules
  • pT4c: both T4a and T4b
  • pT4d: inflammatory carcinoma (involves > 1/3 of the breast skin, primarily a clinical diagnosis)

Notes:
  • Lobular carcinoma in situ (LCIS) is no longer classified as Tis and is now considered a risk factor, not a malignancy
  • For invasive tumors, do not include in situ tumor in the tumor measurement used to determine pT category
  • Round invasive tumor size to the nearest millimeter, except if between 1.0 and 1.4 mm, then round up to 2.0 mm to avoid classifying as pT1mi
  • Do not add tumor dimensions from the needle biopsy to the excision; use the maximum dimension in either the needle biopsy or excision for pT categorization (invasive tumor is larger in the needle biopsy than subsequent excision in 12% of cases, Am J Surg Pathol 2013;37:739)
  • If multiple excisions, may want to report "at least pT_, a more accurate estimate may be based on imaging studies"
  • If there are multiple simultaneous, macroscopically measurable, ipsilateral invasive tumors that are grossly and histologically not connected, use largest individual size, do not sum sizes; can use (m) suffix, e.g., pT1b(m)
  • Contiguous tumor within the pectoralis muscle should be included in the tumor measurement to determine pT category
  • In a postneoadjuvant specimen, measure the largest single contiguous focus; do not include the fibrous tumor bed without viable tumor
Regional lymph nodes (pN)
  • pNX: cannot be assessed
  • pN0: no regional lymph node metastasis histologically
  • pN0(i-): no regional lymph node metastasis by histology or immunohistochemistry
  • pN0(i+): isolated tumor cells (cluster ≤ 0.2 mm and < 200 cells)
  • pN0(mol+): RT-PCR positive but negative by light microscopy
  • pN1mi: micrometastasis (tumor deposit > 0.2 mm and ≤ 2.0 mm or ≤ 0.2 mm and > 200 cells)
  • pN1a: metastasis in 1 - 3 axillary lymph nodes with at least 1 tumor deposit > 2.0 mm
  • pN1b: metastasis in internal mammary sentinel lymph node with tumor deposit > 2.0 mm
  • pN1c: pN1a and pN1b
  • pN2a: metastasis in 4 - 9 axillary lymph nodes with at least 1 tumor deposit > 2.0 mm
  • pN2b: metastasis in clinically detected internal mammary nodes with pathologically negative axillary nodes
  • pN3a: metastasis in ≥ 10 axillary lymph nodes with at least 1 tumor deposit > 2.0 mm or metastasis to infraclavicular lymph node
  • pN3b: positive internal mammary node by imaging with pN1a or pN1b
  • pN3c: metastasis in ipsilateral supraclavicular lymph node

Notes:
  • Lymph nodes, including sentinel lymph nodes, should be bisected along the long axis, not serially sectioned along the short axis; if the bisected halves are thick enough (> 2 mm), they should be further longitudinally sectioned (CAP: Cancer Protocol Templates [Accessed 31 March 2022], Mod Pathol 2010;23 Suppl 2:S26, APMIS 2011;119:868)
  • Regional lymph nodes include axillary, internal mammary, supraclavicular and intramammary
  • Isolated tumor cells = cluster ≤ 0.2 mm and < 200 cells
  • Micrometastasis = deposit > 0.2 mm and ≤ 2.0 mm or ≤ 0.2 mm and > 200 cells
  • Macrometastasis = deposit > 2.0 mm
  • Count cells or measure tumor within a single lymph node cross section
  • Measure only the largest contiguous focus of metastatic tumor cells; adjacent satellites are not included
  • Extranodal extension should be included in the tumor deposit measurement
  • The number of nodes with isolated tumor cells does not change pN category (e.g., 3 nodes with macrometastases plus 1 node with isolated tumor cells is pN1a, not pN2a)
  • Direct extension of tumor into an intramammary lymph node is included as a positive regional lymph node
  • Rounded tumor nodules without nodal tissue present in a nodal drainage area should be considered lymph nodes completely replaced with tumor, unless a vascular wall is present
  • "Clinically detected" is defined as detected by imaging studies (excluding lymphoscintigraphy) or by clinical examination and having characteristics highly suspicious for malignancy or a presumed pathologic macrometastasis based on fine needle aspiration biopsy with cytologic examination
  • In a postneoadjuvant node, measure only the largest contiguous metastatic deposit; do not add separate tumor deposits or include fibrosis without viable tumor
Distant metastasis (M)
  • pM1: distant metastasis histologically proven > 0.2 mm
Prefixes
  • y: preoperative radiotherapy or chemotherapy
  • r: recurrent tumor stage
AJCC prognostic stage groups
  • pTNM, tumor grade, ER, PR and HER2 status are incorporated into prognostic stage groups to refine prognosis
  • Refer to the AJCC 8th edition for the stage group definitions
Registry data collection variables
Histologic grade (G)
  • GX: cannot be assessed
  • G1: low grade (score 3 - 5)
  • G2: intermediate grade (score 6 - 7)
  • G3: high grade (score 8 - 9)

Notes:
  • To assign a histologic grade, assess and combine values for tubule formation (1 - 3), nuclear pleomorphism (1 - 3) and mitotic count (1 - 3) into a score
Gross images

Contributed by Debra L. Zynger, M.D.

Bone metastasis (pM1)

Microscopic (histologic) images

Contributed by Sucheta Srivastava, M.D.

Macrometastasis

Macrometastasis with extranodal extension


Micrometastasis

Isolated tumor cells, pancytokeratin

Additional references
Board review style question #1
What is the pN category for a patient with 1 macrometastasis, 2 micrometastases and 2 nodes with isolated tumor cells?

  1. pNX
  2. pN0(i+)
  3. pN1a
  4. pN2a
  5. pN3a
Board review style answer #1
C. pN1a. The number of nodes with isolated tumor cells does not increase the pN category.

Comment Here

Reference: Breast - Staging
Board review style question #2
Which is the correct pT for a primary breast carcinoma that is 4 mm?

  1. pTis
  2. pTmi
  3. pT1a
  4. pT1b
  5. pT1c
Board review style answer #2
C. pT1a. pT1a is defined as a tumor that is > 1 mm but ≤ 5 mm.

Comment Here

Reference: Breast - Staging
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