TNM Supplement

A Commentary on Uniform Use

Christian Wittekind, James D. Brierley, Anne Lee, Elizabeth Van Eycken, Christian Wittekind, James D. Brierley, Anne Lee, Elisabeth van Eycken

• Publisher: Wiley-Blackwell
• Year: 2019
• ISBN:
  9781119263920
• Edition: 5
• Topic: Medicine
• Subtopic: Oncology

The Union for International Cancer Controls (UICC) TNM classification system is the most widely used cancer classification and staging system in the world. It is used to describe the anatomical extent of disease and it is essential to patient care, research and cancer control.

This fifth edition of the TNM Supplement: A Commentary of Uniform Use offers practitioners a wealth of material intended to complement the systems day-to-day use. The volume features:

• Updated definitions of terms used in cancer staging.
• New sections on carcinomas of the thymus, sarcomas of the spine and pelvis and soft tissue sarcomas of the head and neck, and comprehensive updates to the head and neck carcinomas, carcinomas of the lung and neuroendocrine tumours sections.
• Frequently asked questions from the UICC helpdesk.

The Supplement may be treated as a companion text to the recent eighth edition of the TNM Classification of Malignant Tumours (978-1-119-26357-9), supporting the correct and uniform application of the TNM classification system. The TNM Supplement can also be utilised as a standalone book, providing explanations and examples to answer many questions that arise during the daily use of the TNM cancer classification and staging system, particularly in unusual cases.

CHAPTER 1
EXPLANATORY NOTES – GENERAL

The General Rules of the TNM System

General Rule No. 1

All cases should be confirmed microscopically as malignant tumours including histological type. Any cases not so proved must be reported separately.

Microscopically unconfirmed cases can be staged, but should be analysed separately.

---

Examples

Microscopic confirmation of choriocarcinoma is not required if the serum/urine βHCG level is abnormally elevated.

Microscopic confirmation of hepatocellular carcinoma is not required if the serum AFP level is abnormally elevated in the presence of characteristic radiological appearance.

---

General Rule No. 2 (Table 1.1)

Table 1.1 Definitions of various TNM terms

Definitions Cancer stage (a noun) – ‘the stage’ The UICC has defined the term ‘stage’ as the anatomical extent of disease (UICC 8th edition [2, 3]). Cancer staging (a verb) – ‘to stage’ It refers to the process of deriving the ‘stage’. This includes the investigational work‐up, most usually examination and imaging studies, or, alternatively, verifying or consulting the T, N and M category definitions and combinations. Stage migration The term ‘stage migration’ describes a change in the proportion of T, N or M categories following introduction of new means of assessing disease extent in populations of patients rather than in individual patients. Stage shift The term ‘stage shift’ describes a change in the pattern of stage distribution within a defined population to a lower stage following the introduction of early detection or screening programs, or to a higher stage when access to care becomes limited. Downstaging/downsizing/upstaging/understaging The term ‘downstaging’ is used to describe a reduction in the T or N category after neoadjuvant therapy. The term ‘downsizing’ is used to describe a reduction in size of the tumour after neoadjuvant therapy. The terms ‘upstaging’ and ‘understaging’ are occasionally used, and typically relate to different diagnostic accuracy of various staging investigations. We do not recommend their use.

Two classifications are described for each site, namely:

1. Clinical classification: the pre‐treatment clinical classification designated TNM (or cTNM) is used to select and evaluate therapy. This is based on evidence acquired before treatment. Such evidence is based on physical examination, imaging, endoscopy, biopsy, surgical exploration and other relevant examinations.
2. Pathological classification: the post‐surgical histopathological classification, designated pTNM, is used to guide adjuvant therapy and provides additional data to estimate prognosis and calculate end results. This is based on evidence acquired before treatment, supplemented or modified by additional evidence acquired from surgery and from pathological examination.

The pathological assessment of the regional lymph nodes (pN) entails removal of at least one lymph node to validate the absence or presence of cancer. It is not necessary to pathologically confirm the status of the highest N category to assign the pN. The assignment of the regional lymph nodes (pN) requires pathological assessment of the primary tumour (pT), except in cases of an unknown primary (T0).

An excisional biopsy of a lymph node without assessment of the pT category is insufficient to fully evaluate the pN category and is considered a clinical classification.

---

Example

The examination of axillary lymph nodes (sentinel lymph node or non‐sentinel lymph nodes) with only a biopsy diagnosis of the primary tumour in the breast is classified as cN, e.g. cN1, if there are metastases in movable ipsilateral level I, II axillary lymph node(s).

---

The pathological assessment of distant metastasis (pM1) entails microscopic examination.

TNM is a dual system that includes a clinical (pre‐treatment or after neoadjuvant radio‐/chemo‐/radiochemotherapy but before surgery) and a pathological (post‐surgical histopathological) classification. It is imperative to differentiate between them since they are based on different methods of examination and serve different purposes. The clinical classification is designated TNM or cTNM; the pathological, pTNM. When TNM is used without a prefix, it implies the clinical classification (cTNM). Microscopic confirmation does not in itself justify the use of pT. The requirements for pathological classification are described in Chapter 3 on page 157.

Biopsy provides the diagnosis, including histological type and grade (if possible). The clinical assessment of tumour size should not be based on the biopsy.

In general, the cTNM is the basis for the choice of treatment and the pTNM is the basis for prognostic assessment. In addition, the pTNM determines adjuvant treatment. Comparison between cTNM and pTNM can help in evaluating the accuracy of the clinical and imaging methods used to determine the cTNM. Therefore, it is important to retain the clinical as well as the pathologi...