Cancer Staging: Rules for Staging.
In this video you will learn about:General Rules for Cancer Staging, Clinical Classification
(Before Treatment), Pathological Classification (After Surgery) Cancer stage is classified
using the Tumour, Node, Metastasis system, also known as TNM.
TNM classification defines the extent of the primary tumour, the absence or presence and
extent of regional lymph node metastasis and the absence or presence of distant metastasis.This
classification follows a sequential process where cancer starts in the organ of origin
(for example, breast cancer starts in the breast), it then spreads to local tissues
(this means it can invade the breast tissue), invades lymphatics or blood vessels then it
colonizes lymph nodes or other organs (for example, the bones, the lung and the liver).
For example, a mammogram is performed showing left breast cancer.
A CT scan of the thorax shows a 3cm mass in the left breast and axillary lymph node.
An x-ray and CT scan show extensive disease with metastatic breast cancer to the right
hip.
This is classified as cT2N1M1 Tumours are classified both before the start of treatment
and after surgical treatm-ent.
This is known respectively as the clinical and pathological classification.
Stage and stage group refers to the anatomical extent of disease.
Prognostic group combines anatomical, namely stage and non-anatomical factors, such as
age or tumour grade.
Clinical Classification (Before Treatment) cTNM is the clinical classification given
to tumours.
It is assigned before treatment or surgery.
Pre-treatment clinical classification is based on evidence acquired before treatment.
This evidence is gathered from physical examination and procedures including: Endoscopy, Biopsy
Surgical exploration (for example, laparotomy).
Note: this is not the sa me as surgical treatment and surgical excision.
This classification helps to select and evaluate the type of therapy to be used.For example,
a patient has a lung tumour measuring 2cm in size.
There is no evidence of lymph node involvement or metastases.
The clinical stage is cT1bN0M0, or clinical stage IA2.
Primary Tumour (T) When assigning a clinical classification to
the primary tumour, the following combination of letters and numbers is used:cTX means the
primary tumour cannot be assessed, cT0 means there is no evidence of primary tumour, cTis
means the carcinoma is in situ, and, cT1-T4 refers to the increasing size and/or local
extent of the primary tumour.
Regional Lymph Nodes (N) When assigning a clinical classification to
the regional lymph nodes, the following combination of letters and numbers is used:, cNX means
the regional nodes cannot be assessed, cN0 means there is no regional lymph node metastasis
and cN1-N3 refers to the increasing involvement of regional lymph nodes Distant Metastasis
(M) When assigning a clinical classification to the absence or presence of distant metastases,
the following combination of letters and numbers is used: cM0 means there is no distant metastasis,
cM1 means there is distant metastasis.
In some cancers the categories are further subdivided.
An example is in rectal cancer where M1 can be subdivided into M1a, M1b and M1c depending
on where the metastases are and how many are found.
Pathological Classification (After Surgery) pTNM is the pathological classification of
the extent of disease.
This classification is assigned after surgery.
It helps guide adjuvant therapy and estimate prognosis.
Usually, the pathological (pTNM) categories correspond to the clinical (cTNM) categories
but there are exceptions.
The patient in the previous example has surgery to treat their cancer.
The pathology after surgery shows that the tumour is 1.8cm in size.
The pathological classification of the tumour following surgery is pT1b.
The pathology also reported a lymph node was involved.
Therefore, the pathological classification is pT1bpN2cM0 Primary Tumour Classification
(pT) The pathological assessment of the primary
tumour is only used if there has been a resection of the primary tumour.
Regional Lymph Node Classification (pN) The pathological assessment of the regional
lymph nodes (pN) involves the removal of the lymph nodes to show if there are any regional
lymph node metastasis.
An excisional biopsy of a lymph node is a clinical classification as a lymph node dissection
is not being performed.
Distant Metastasis Classification (pM) The pathological assessment of distant metastasis
(pM) involves microscopic examination of metastatic deposits.
At least a biopsy must be performed to classify as pM1.
In this video you learned about general rules for cancer staging.
For a list of helpful resources and publications on TNM staging, visit the UICC website www.uicc.org/resources/tnm