General Information

When diagnosing cancer, patients are often confronted with confusing abbreviations (e.g. in a doctor's letter or pathology report), which are difficult for non-medical staff to understand. Therefore, we have briefly summarized the most important abbreviations for you.

Different systems are used to describe cancer. The internationally uniform classification of tumors is important for the treatment of cancer and for assessing the potential further course of the disease.

To describe the type of cancer, the diagnostic key is used, such as the International Classification of Diseases (ICD). The current international version (2020) is ICD-10 and for Germany ICD-10-GM (German Modification).

Here, each disease (including diseases other than cancer) is characterized by a combination of a letter and a number. For example, C56 stands for ovarian cancer, C50 for breast cancer, C34 for lung cancer, I21 for acute myocardial infarction (heart attack), J10 for influenza, etc. Other numbers are used to define the disease even more precisely, such as the location of a tumor. For example, C34.3 stands for a tumor in the lower lobes of the lung.


To define how far a tumor has already spread in a patient's body, the so-called TNM system is often used. Here T stands for tumor, N for Nodus (lymph node) and M for metastases.

  • T describes the spread and size of the primary tumor. The numbers 1 to 4 (T1 to T4) describe the increasing spread and size of the primary tumor. Special case T0 is the rare CUP syndrome (Cancer of Unknown Primary). This means that one or more metastases have been found, but it is not clear where they originate and where the primary tumor is located. Tis stands for tumor in situ. These are early forms of cancer that have not yet grown into the neighboring tissue.

  • N describes whether metastases are present in regional lymph nodes (lymph nodes that are directly assigned to an organ). N0 means that no cancer cells were detectable in regional lymph nodes. N1 to N3 describe the infestation of more and more regional lymph nodes, which are also further away from the tumor.

  • M describes whether metastases are present in other organs. M0 means that no distant metastases are present and M1 means that distant metastases have been detected.

For example, T1N0M0 would indicate that it is a small tumor that has not yet metastasized to regional lymph nodes and other organs. In contrast, T4N3M1 would mean that the patient has a fairly large tumor that has metastasized in many lymph nodes as well as in one or more other organs.

Furthermore, a distinction can be made between clinical cTNM and postoperative or pathological pTNM classification.

  • In the clinical classification, the assessment of tumor spread is based, for example, on physical examinations and imaging procedures.

  • The postoperative or pathological classification is based on the histopathological examination of the tumor tissue after surgery.

Both classifications complement each other.

Additional capital or lower case letters, either preceding or following the name, may provide further information about the cancer. Examples are V (venous invasion, indicates whether cancer cells have been found in the walls of blood vessels), L (invasion of lymphatic vessels), Pn (tissue surrounding nerves, attacked by tumour cells) or a, b, c and d (a more precise statement about the size and spread of the primary tumour T is possible, intermediate stages can be better described, e.g. T2a, T2b etc.).

Other Categories of the TNM-System

Grading" defines the degree of change in cancer cells compared to normal healthy body cells. A statement can also be made as to which tissue the tumour cells originate from.

  • G1 means the tissue is well differentiated (less malignant),

  • G2 means the tissue is moderately differentiated,

  • G3 means the tissue is poorly differentiated and

  • G4 means the tissue is not differentiated (very malignant).

The less a cancer cell resembles the tissue from which it originates, i.e. the less differentiated it is, the more malignant it is. GX means that the degree of differentiation cannot be assessed.

The R classification provides information about a residual tumour (residual tumour) after an operation. In this case, it is checked after an operation whether the tumour could be completely removed or whether there are still residual tumours in the body.

  • R0 means that no residual tumor can be detected with a microscope.

  • R1 means that a residual tumour can be detected with a microscope.

  • R2 means that a residual tumour can be seen with the eye and

  • RX means that the residual tumor is not assessable.

Overview of abbreviations:


CUP-Syndrom (Cancer of Unknown Primary), not known where primary tumor is located


Tumor in situ, early form of cancer


Primary tumor smaller than 2 cm


Size of primary tumor is 2-5 cm


Primary tumor is bigger than 5 cm


Tumour of any size with direct extension in the neighbourhood


No infestation of the neighbouring lymph nodes


Few metastases in neighbouring lymph nodes


More metastases in neighbouring lymph nodes


Many metastases in neighbouring lymph nodes


Lymph node infestation cannot be assessed


No detection of distant metastases


Detection of distant metastases


Metastasis cannot be assessed


Invasion of veins


Invasion of lymph vessels


Perineural invasion


Tissue is well differentiated


Tissue is moderately differentiated


Tissue is poorly differentiated


Tissue is not differentiated


Degree of differentiation cannot be assessed


No residual tumor can be detected with microscope


Residual tumour can be detected with microscope


Residual tumour can be seen with the eye


Residual tumor is not assessable


Staging" is used to describe how far advanced the cancer is, what stage it is in, and what stage it has reached. Staging, i.e. the division into the different stages of the disease, is different for each type of tumor. In some tumor types, even small tumors are very dangerous and some of them have a good chance of healing even if they have metastases. Often a system of the Union Internationale contre le Cancer (UICC) is used for staging, which is based on the TNM classification. For most tumor types there are stages 0 to IV. For the different tumor types it is determined individually which T, N and M categories correspond to which stage of cancer.

Stage 0
Early forms of cancer
Stage I and II
Tumors that are still growing within the organ boundaries
Stage III
Tumors that have already spread locally and have formed lymph node metastases
Stage IV
Tumors that have already formed distant metastases
Feb 20, 2020 By Dr. Julia Reiser