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Since 1893 there has been an international classification
for coding mortality. When the World Health Organization (WHO)
was established after the Second World War, it took charge
of publishing these classifications. The Sixth Revision of
the International Statistical Classification of Diseases,
Injuries, and Causes of Death (ICD) (9)
was published in 1948 and soon afterwards it began to to code
and tabulate mortality and morbidity
data.
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In the early years of nomenclature and coding of neoplasms
(1950s and 1960s), the principal system for classifying
diseases was the ICD series published by WHO. Eventually
ICD was used to code and tabulate the diagnoses on medical
records for the purpose of storage and retrieval, and
Chapter II of ICD was always assigned to neoplasms.
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In the Sixth Revision of ICD in 1948, the classification
of neoplasms has been based primarily on topographic site
and behavior (that is, whether the neoplasm was malignant,
benign, or not specified). Except for lymphatic and hematopoietic
neoplasms, choriocarcinoma,
melanoma, and certain benign neoplasms, there had been no
codes assigned for other histologic types.
The first code manual for the morphology of neoplasms was
published by the American Cancer Society (ACS) in 1951 as
the Manual of Tumor Nomenclature and Coding (MOTNAC) (10).
Tumor codes consisted of a two-digit code for morphology with
a third digit denoting the behavior of the neoplasm. This
code was the basis of a statistical code proposed by WHO in
1956 for tumor morphology.
In the 1960s, with the aid of the ACS, the College of American
Pathologists (CAP) published the Systematized Nomenclature
of Pathology (SNOP) (11).
SNOP provided a morphology code including two sections, 8
and 9 on neoplasms and a completely new, highly detailed
topography code to cover the whole body. An agreement stipulated
that ACS could use the SNOP neoplasm morphology sections 8
and 9 and publish these with their own topography codes. Since
cancer registries had always used the malignant neoplasm section
of ICD for topography, ACS based its topography on the malignant
neoplasm section of ICD-8. A new edition of MOTNAC appeared
in 1968, and was used extensively by cancer registrars.
In 1968, the International Agency for Research on Cancer
(IARC) was asked by WHO to make recommendations about the
content and structure of the neoplasm chapter for ICD-9 in
consultation with the cancer and ICD units of WHO and various
national bodies. Physicians expressed a desire for a cancer
supplement that would also include morphology. Many consultants
worldwide made suggestions for the neoplasm section of ICD-9
and emphasized the need for the coding of morphology or histology
of tumors. The consultants suggested using the 1968 edition
of MOTNAC as a basis for the morphology (histology) section:
the morphology section of MOTNAC had been based on the neoplasm
section of SNOP published by CAP. MOTNAC was widely accepted
and translated into a number of languages.
Working parties for ICD-9 also recommended a requirement
that the morphology of a tumor be recorded and coded. For
many years, oncologists
had realized that knowledge solely of the site or topography
of a tumor was not sufficient for planning treatment or conducting
research. For example, incidence and survival rates differ
according to the histologic type of the tumor.
The working parties further recommended that a special adaptation
of ICD, designated the International Classification of Diseases
for Oncology (1),
be created as the successor to MOTNAC for use by specialists
in oncology who require greater detail of histologic classification.
The recommendation was endorsed by a Study Group on the Classification
of Diseases convened by WHO in 1971.
In 1976, WHO published the first edition of the International
Classification of Diseases for Oncology, which had a topography
section based on the malignant neoplasm rubrics
of ICD-9 and a morphology section that expended the MOTNAC
morphology code by one digit. CAP adopted the morphology of
ICD-O for its revised edition of SNOP called the Systematized
Nomenclature of Medicine (SNOMED) (2).
The topography in SNOMED was again entirely different from
that of ICD-O. Some of the SNOMED morphology terms for non-neoplastic
tumor-like lesions
and premalignant conditions are listed in ICD-O to help users
differentiate these terms from those of true neoplasms. The
SNOMED codes are no longer given because of continual changes
to the codes, now principally published on the Internet. An
ICD-O user simply needs to recognize that a term referenced
in ICD-O-3 to SNOMED is not a neoplasm.
The Second Edition of ICD-O (4)
was developed by a WHO/IARC working party and edited by Constance
Percy, Valerie Van Holten, and Calum Muir. It was published
by WHO in 1990 for use in cancer registries and by departments
specializing in cancer begining with cancers diagnosed on
January 1, 1992 through cases diagnosed on December 31, 2000.
The Second Edition of the International Classification of
Disease for Oncology is a dual classification and coding system
for both topography and morphology. 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 non-malignant neoplasms than is possible in
ICD-10. The Second Edition of ICD-O has been used extensively
throughout the world and has been translated into many languages,
including Chinese, Czech, French, German, Greek, Italian,
Japanese, Portuguese, Russian, Slovak, and Spanish.
The Third Edition of ICD-O (ICD-O-3) has also been developed
by a working party convened by WHO/IARC. The morphology codes
for neoplasms have been revised, especially for lymphomas
and leukemias. The codes incorporate the WHO classification
(21, 22), which superseded
the REAL (Revised European-American Lymphoma) classification
for lymphomas (6)
and the FAB (Frech-American-British) classification for leukemias
(7). The Third Edition
also recognizes the WHO classification of myeloid leukemias,
including distinct combinations of morphology and cytogenetic
abnormalities. An example is M-9863/3, chronic
myelogenous leukemia, Philadelphia chromosome
(Phl) positive, which is also referred to as chronic myelogenous
leukemia, t(9;22)(q34;q11)
or chronic myelogenous leukemia, BCR/ABL. ICD-O-3 was intended
to be used in cancer registries throughout the world beginning
with cancers diagnosed on January 1, 2001 and forward. However,
there are a few countries that have decided to delay implementation
of ICD-O-3 until 2003 and 2004 due to the many changes incorporated
in ICD-O-3. Click here
to go to the ICD-O-3 training module.
Conversions
Conversion algorithms (comparability codes) from ICD-O, Third
Edition, to other coding systems are available. There is no
change in topography between the Second and Third Editions
of ICD-O, and the major changes in the morphology section
are in the lymphomas and leukemias.
Click here
to view a diagram of historical lineage of ICD-O.
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