ICD-O-3
International Classification of Diseases for Oncology
3rd Revision

The abbreviation ICD-O means " International Statistical Classification of Diseases for Oncology"; the number 3 signifies its 3rd revision. This classification was published by the World Health Organization and is being translated into German by DIMDI. After the Federal Cancer Registry Act and its continuation in the State Cancer Registry Acts ICD-O is used in the German Cancer Registries. As a German translation of ICD-O-2 the so-called Tumorhistologieschlüssel (THS) and theTumorlokalisationsschlüssel have been used. They are almost identical with the original classification of WHO.

• Download of the German ICD-O-3

Basic information on ICD-O-3

The ICD-O-3 is a dual classification and coding system for both topography and morphology of a neoplasm. The topography code uses the same three- and four-character categories as ICD-10 for malignant neoplasms (C00-C80), allowing greater specificity for the site of nonmalignant neoplasms than is possible in ICD-10. The morphology code describes the specific histologic cell type and its behaviour. It indicates the specific histologic term.

ICD-O-3 consists of an introduction and five main sections:

• Introduction
  It describes the historical background of the ICD-O-3, some differences to the ICD-10 and gives some basic information on the structure of the ICD-O-3.
• Instructions for Use
  It includes instructions for use and rules for implementation in tumor (cancer) registries and pathology laboratories and gives some examples of coding.
• Topography - Numerical List
  The topography section has been adapted from the malignant neoplasm section of Chapter II of ICD-10. These topography terms have four-character codes that run from C00.0 to C80.9. A decimal point (.) separates subdivisions of the three-character categories. There have been no changes between the topography of ICD-O-2 and ICD-O-3.
• Morphology - Numerical List
  Morphology terms have five-digit codes ranging from 8000/0 to 9989/3. The first four digits indicate the specific histologic term. The fifth digit, after the slash or solidus (/), is a behavior code, which indicates whether a tumor is malignant, benign, in situ, or uncertain whether malignant or benign.
  A separate one-digit code for histologic grading or differentiation is provided. For a lymphoma or leukemia, this element of the code is used to identify T-, B-, Null-, and NK-cell origin.
• Alphabetic Index
  The alphabetic index is used to code both topography (anatomical sites) and morphology (histologic terms). The index also includes selected tumor-like lesions and conditions. Topography codes are identified by the letter C, the first character of codes in Chapter II of ICD-10. The terms are listed under both the noun and the adjective. For example, basophil adenocarcinoma is listed under B for "basophil" and under A for "adenocarcinoma, basophil".
• Differences in Morphology Codes between Second and Third Editions
  This section consists of a list of terms now considered malignant, a list of all new morphology code numbers and a list of all terms and synonyms added to existing code definitions.