Breast Cancer staging and TNM classifications
NOTE: In January 2018 The American Joint Committee on Cancer (AJCC) updated their 8th Edition of the staging classifications for breast tumors.
You can find a summary of the main changes, including amendments to the TNM categories, for staging breast cancer by clicking HERE. We will also be fully updating our staging articles on this site to include all the new information.
Breast cancer is typically described in stages, according to the presence and size of the tumor and its metastasis in the axillary lymph nodes, and other factors. T refers to the tumor size. For breast tumors, bigger than 2cm changes the T category. N refers to ‘node status‘, which changes as the tumor spreads into lymph nodes. M refers to ‘metastasis‘, which indicates that the cancer has spread to places beyond the breast. The TNM classifications were developed by the American Joint Committee on Cancer.
This page is still OK for reading, but it is getting fairly old… So we have created a new version of this page with more up-to-date information on TNM classifications.
|T0||No evidence of primary tumor|
|T1a||Carcinoma in situ|
|T1||< or = 2 cm|
|T1m1c||microinvasion .1 cm or less|
|T1a||>.1 to .5 cm|
|T1b||>.5 to 1 cm|
|T1c||>1 to 2 cm|
|T2||>2 to 5 cm|
|T4||Any size tumor with direct extension to : a) Chest wall or b) skin|
|T4a||Chest wall, not including pectoralis muscle|
|T4b||Skin edema, ulceration, satellite skin nodule|
|T4c||4a and 4b|
|Nx||Regional lymph nodes cannot be removed|
|N0||No regional lymph node metastasis|
|N1||Metastasis to movable ipsilateral axillary lymph nodes|
|N2||Metastases in ipsilateral axillary lymph nodes fixed of matted (N2a) or met. only in clinically apparent ipsilateral mammary nodes without clinically evident axillary lymph nodes. ( N2b)|
|N3||Metastases in ipsilateral infraclavicular lymph nodes (N3a) or clincially apparent ipsilateral internal mammary lymph nodes (N3b) or ipsilateral supraclavicular lymph nodes (N3c)|
|MX||Distant metastasis cannot be assessed|
|M0||No distant metastasis|
Sub categories of the T4 classifcation, using P factors (pathology)
Sometimes the T classification is modified by what might be called “P factors“, which refer to clinical observations made by a pathologist examining lymph node tissue, using a microscope. “P” indicates ‘proved‘ by pathology.
Regional lymp nodes cannot be assessed, No regional l. node metastasis histologically, Metastasis in 1-3 axillary lymph nodes
|pN1mi||Micrometastasis > 0.2 mm to < 2 mm|
|pN1a||Metastasis > 0.2 mm + at least one node > 2 mm|
|pN1b||Metastasis in internal mammary l. nodes detected by SLN|
|pN1c||Metastasis in 1-3 axill. + internal mammary l. nodes by SLN|
|pN2||Metastases in 4-9 ipsilateral lymph nodes|
|pN2a||Metastases in 4-9 axillary + at least one > 2 mm|
|pN2b||Metastasis in clinically apparent internal mammary l. nodes without axillary lymph nodes metastasis|
|pN3a||Metastases in 10 or more ipsilateral axillary lymph nodes or ipsilateral infraclavicular|
|pN3b||Clinically apparent internal mammary l. nodes with 1 or more axillary l. nodes or more than 3 axillary lymph nodes with microscopic met. in internal mammary lymph nodes|
|pN3c||Ipsilateral supraclavicular l. nodes|
Clinical stages of breast cancer based on TNM grouping
Based on of T, N, and M criteria, the following stages, ranging for zero to IV, have been identified for breast cancer. Breast cancer stages basically describe the ‘extent‘ of the breast cancer, and naturally have implications for treatment strategies.
|Breast cancer stages||Classification criteria based on TNM|
|Stage 0||Tis, N0, M0|
|Stage I||T1, N0, M0|
T0, N1, M0 or
T1, N1, M0 or
T2, N0, M0
T2, N1, M0 or
T3, N0, M0
T0, N2, M0 or
T1, N2, M0 or
T2, N2, M0 or
T3, N1, M0 or
T3, N2, M0
T4, N0, M0 or
T4, N1, M0 or
T4, N2, M0
|Stage IIIC||any T, N3, M0|
|Stage IV||any T, any N, M1|
Changes to the TNM classification systems in the 7th edition AJCC cancer staging manual
The newest (7th) edition of the American Joint Committee on Cancer, Cancer Staging Manual has only minor changes from the 6th edition.
Within the ‘P‘ or pathology categories, only ductal and lobular carcinoma in situ (DCIS, LCIS), and isolated Paget’s disease of the nipple are classified as pTis. (is for ‘in situ) So-called ‘precursor‘ breast neoplasm such as atypical ductal or lobular hyperplasia (ADH, ALH) are no longer included. (In situ lesions have also been called T1a)
Some new guidelines are also given reflecting the classification of ‘micro metastasis‘ in the regional lymph nodes. Now, small clusters of cancer cells no larger than 0.2 mm, or non confluent or nearly confluent clusters of cells not exceeding 200 cells in a single histologic lymph node cross section, may be classified as isolated tumor cells (pN0(i+)).
And finally, Stage I breast tumors have now been subdivided into Stage IA and Stage IB, with stage IB including small tumors (TI) with lymph node micro metastases (N1mi).
Staging classification may be updated again with respect to biological tumor features
With ongoing breast cancer research, it is likely that the TNM classification system will need to be updated again from time to time. Nuclear ‘grading‘ factors have always been considered in parallel to the anatomically-based staging criteria. Hormone receptor status and other molecular/genetic features of a specific breast cancer may also be included in the staging classifications at some point.
Everything you need to know about TNM classification is listed above… But below are some quick Q&A anyway:
- Are all cancers staged with TNM classification? Most types of cancers have TNM designations, but some do not.
- What does TNM mean? Tumor Nodes Metastases.
- How does TNM fit together? Your doctor puts the TNM results together to give you your overall stage. This is usually what the doctor writes on your test forms. For instance, you might see a tumor described as T2 N0 M0. This would be a single tumor 2.1 to 5 cm across, no evidence of spread to any lymph nodes, and no evidence of spread outside the breast.
- American Joint Committee on Cancer, Cancer Staging Manual. Sixth Edition p. 227-228, 2002.
- Breast. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 347-76.
- Singletary SE, Connolly JL. Breast cancer staging: working with the sixth edition of the AJCC Cancer Staging Manual.CA Cancer J Clin. 2006 Jan-Feb;56(1):37-47
- Amir H, Azizi MR, Makwaya CK, Jessani S. TNM classification and breast cancer in an African population: a descriptive study. Cent Afr J Med 1997; 43: 357–359.
- Jeruss, JS., Mittendorft, EA., Tucker, SL, Gonzales, AM., Buchholz, TA., Sahin, AA., Cornmier, JN., Buzdar, AU., Hortobagyi, GN., Hunt, KK. Staging of Breast Cancer in the Neoadjuvant Setting Cancer Res., (August 2008) 68(16): 6477 – 6481.
- AJCC (American Joint Committee on Cancer) Cancer Staging Manual, 7th ed, Edge, SB, Byrd, DR, Compton, CC, et al (Eds), Springer-Verlag, New York, 2010. p.347-377.
- Al-Raheem, SN., Atoum, MF., Hourani, HM., Shoter, A., AlMuhrib, TK. TNM staging and classification (familial and nonfamilial) of breast cancer in Jordanian females. Indian Journal of Cancer,( April 2010)
- Veronesi, U., Zurrida, S., Viala, G., Galimberti, V., Arnone, P. Nole, F. Rethinking TNM: A Breast Cancer Classification to Guide to Treatment and Facilitate Research. The Breast Journal (May-June 2009)Volume 15, Issue 3, pages 291–295.
- Mathew Purdom, Michael L. Cibull, Terry D. Stratton, et al., “Should Histologic Grade Be Incorporated into the TNM Classification System for Small (T1, T2) Node-Negative Breast Adenocarcinomas?,” Pathology Research International, (2011) 4 pages.
- P. L. Fitzgibbons, D. L. Page, and D. Weaver, “Prognostic factors in breast cancer: College of American Pathologists consensus statement 1999,” Archives of Pathology & Laboratory Medicine, vol. 124, pp. 966–978, 2000.
- L. Tabár, H. H. Chen, and S. W. Duffy, “A novel method for prediction of long-term outcome of women with T1a, T1b, and 10-14 mm invasive breast cancers: a prospective study,” The Lancet, (2000) vol. 355, no. 9212, p. 1372.
- L. Tabar, H.-H. T. Chen, and H.-H. T. Chen, “Mammographic tumor features can predict long-term outcomes reliably in women with 1-14-mm invasive breast carcinoma: suggestions for the reconsideration of current therapeutic practice and the TNM classification system,” Cancer, (2004)vol. 101, no. 8, pp. 1745–1759
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