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Tumor, Node, Metastasis (TNM) staging classification for breast cancer

Author
Daniel F Hayes, MD
Section Editor
Anees B Chagpar, MD, MSc, MA, MPH, MBA, FACS, FRCS(C)
Deputy Editor
Sadhna R Vora, MD

INTRODUCTION

The Tumor, Node, Metastasis (TNM) staging system for breast cancer is an internationally accepted system used to determine the disease stage. This disease stage is used to determine prognosis and guide management. It is also used to facilitate discussions about treatment and prognosis between collaborating providers, as well as between providers and patients.

The TNM staging system correlates important tumor characteristics with survival data to help estimate and follow outcomes. It is based upon a retrospective analysis of survival in diverse samples of patients representing all stages of disease. It reflects the clinical evaluation methods and treatments that are applied to the particular study population. While an individual patient's clinical course and outcome cannot be predicted with certainty, available survival data can help direct treatment decisions and provide an estimate of the likely prognosis.

Periodic revisions are necessary because advanced imaging techniques and treatments evolve and impact survival. The eighth edition of the TNM staging system, which is effective as of January 1, 2018, includes anatomic stage groups (table 1) as well as prognostic stage groups, which incorporate biomarker testing (table 2) [1]. Staging has traditionally relied on tumor size, involvement of lymph nodes, and presence of metastatic disease. The eighth edition incorporates biologic markers, which improve prognostic discrimination over anatomic staging alone. Outside of the United States, the Union for International Cancer Control (UICC) has implemented the eighth edition changes as of January 1, 2017.

The rationale and data supporting the eighth edition of the TNM staging system are discussed here. The initial evaluation, clinical manifestations, diagnosis, treatment, and prognosis of breast cancer are reviewed elsewhere. (See "Overview of the treatment of newly diagnosed, non-metastatic breast cancer" and "Clinical features, diagnosis, and staging of newly diagnosed breast cancer".)

REVISIONS IN STAGING FROM THE SEVENTH TO THE EIGHTH EDITIONS

The eighth edition of the American Joint Committee on Cancer (AJCC) staging manual, effective January 1, 2018, outlines a new prognostic staging system that relies not only on the anatomic extent of disease, but also on prognostic biomarkers. In areas in which biomarker testing is performed, prognostic stage groups should be utilized. Although the prognostic staging system provides refined information regarding outcomes, the anatomic staging was retained to allow a common lexicon for patients treated worldwide who may not have access to biomarker testing. Additionally, the anatomic staging system provides a link to cases treated historically, staged using previous editions of the TNM system.

                   
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Literature review current through: Nov 2017. | This topic last updated: Aug 15, 2017.
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References
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  1. AJCC (American Joint Committee on Cancer) Cancer Staging Manual, 8th edition, Amin MB, Edge SB, Greene FL et al (Eds), Springer, Chicago 2017.
  2. Sparano JA, Gray RJ, Makower DF, et al. Prospective Validation of a 21-Gene Expression Assay in Breast Cancer. N Engl J Med 2015; 373:2005.