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Breast Cancer: Changes in 8th AJCC TNM Classification

The eighth edition of the TNM classification of AJCC (American Joint Commission of Cancer) (2) was released in May this year. This was the first update since the 7th edition of 2009.


The changes from the 7th edition that are of clinical relevance include:

  • Immunohistochemical tumour markers – ER, PR, HER2 – that have practical importance for therapy are now incorporated into the staging system.
  • The staging system now incorporates genomic assays – OncotypeDx, Mammaprint, PAM 50 (if available) – to downstage some oestrogen receptor-positive, lymph node-negative tumors.
  • Lobular carcinoma in situ (LCIS) has been removed from the staging system and is no longer part of Tis. This is because LCIS is now considered as a risk factor for invasive disease, and is no longer thought to represent malignant change.
  • T staging – clarity as to staging of post-neoadjuvant treatment:
    • pathological T category (ypT) is to use the largest focus of residual tumour, if present. Treatment-related fibrosis adjacent to residual invasive carcinoma is not included in the ypT maximum dimension*
  • N staging – modifiers added:
    • (f) modifier added to N category indicates diagnosis made by either FNA or core needle biopsy. This usually applies to cN staging before definitive resection or neoadjuvant therapy.
    • (sn) and (f) modifiers – denote confirmation of metastasis by SLN or FNA/needle biopsy with NO further resection of nodes.

Herewith a useful summary from the abstract of the article in the American Cancer Society’s journal,
CA: A Cancer Journal for Clinicians, Volume 67, Issue 4 July/August 2017 Pages 290–303. (1)

ABSTRACT: The revision of the eighth edition of the primary tumor, lymph node, and metastasis (TNM) classification of the American Joint Commission of Cancer (AJCC) for breast cancer was determined by a multidisciplinary team of breast cancer experts. The panel recognized the need to incorporate biologic factors, such as tumor grade, proliferation rate, estrogen and progesterone receptor expression, human epidermal growth factor 2 (HER2) expression, and gene expression prognostic panels into the staging system. AJCC levels of evidence and guidelines for all tumor types were followed as much as possible. The panel felt that, to maintain worldwide value, the tumor staging system should remain based on TNM anatomic factors. However, the recognition of the prognostic influence of grade, hormone receptor expression, and HER2 amplification mandated their inclusion into the staging system. The value of commercially available, gene-based assays was acknowledged and prognostic input added. Tumor biomarkers and low Oncotype DX recurrence scores can alter prognosis and stage. These updates are expected to provide additional precision and flexibility to the staging system and were based on the extent of published information and analysis of large, as yet unpublished databases. The eighth edition of the AJCC TNM staging system, thus, provides a flexible platform for prognostic classification based on traditional anatomic factors, which can be modified and enhanced using patient biomarkers and multifactorial prognostic panel data. The eighth edition remains the worldwide basis for breast cancer staging and will incorporate future online updates to remain timely and relevant.

*A lower case prefix describes the time point in a patient’s cancer continuum when stage is assigned, including:

  • c: clinical
  • p: pathological
  • Yc/yp: post neoadjuvant (radiation or systemic)
  • a: autopsy

Reference:

  1. Giuliano AE, Connolly JL, Edge SB, et al. Breast Cancer-Major changes in the American Joint Committee on Cancer eighth edition cancer staging manual. CA Cancer J Clin. 2017;67:290–303. doi: 10.3322/caac.21393
  2. https://cancerstaging.org/Pages/default.aspx

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