Digestive System Tumours Breast tumoursSoft tissue and bone tumoursFemale genital tumours Contents
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Edited by | WHO Classification of Tumours Group (World Health Organization) |
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Country | France |
Discipline | Tumours |
Publisher | International Agency for Research on Cancer |
Preceded by | International Histological Classification of Tumors |
The WHO Classification of Tumours, more commonly known as the WHO Blue Books, is a series of books that classify tumours. They are compiled by expert consensus and published by the World Health Organization's (WHO) International Agency for Research on Cancer (IARC). They appear in print and online in a series of 15 books, each of which focuses on a major tumour group and defines the cause, mechanism, signs and symptoms, basic structure, diagnosis, epidemiology and outcomes of up to 300 types of tumours.
The project was started by the WHO in 1956 and the first series of books was published between 1967 and 1981, as the International Histological Classification of Tumors series. A fifth series was released in 2019. Terms included in the books appear in the international classification of diseases for tumours.
The classifications are regularly updated by an editorial board composed mostly of practicing pathologists. The method of classifying tumours in the Blue Books was discussed in an accompanying article in the International Journal of Cancer in June 2020, titled "WHO Classification of Tumours: How should tumors be classified? Expert consensus, systematic reviews or both?" [1]
The WHO Classification of Tumours series, more commonly known as the WHO Blue Books, published by the WHO's IARC, is a series of books that classify tumours according to principally its location and histopathology. [2] [3] They are compiled by expert consensus, teams of specialists at the International Agency for Research on Cancer, who summarize information from literature. [1] Terms included in the books appear in the international classification of diseases for tumours. [4] [5]
They are published as a series of 15 books, in addition to a website, which provide information on cancer diagnosis, research, treatment and outcomes, particularly for pathologists and cancer researchers. [1] [6] Each book defines the cause, mechanism, signs and symptoms, basic structure, diagnosis, epidemiology and outcomes of up to 300 types of tumours. [6] Between 150 - 200 authors, including radiologists, surgeons, physicians and epidemiologists, contribute to each book. [2]
The WHO Classification of Tumors Group is headed by Ian Cree. [3] The classifications are updated regularly by an editorial board composed mostly of practicing pathologists, [6] [7] who review and agree on definitions and criteria for each tumor. [6]
The editorial board consists of standing members and expert members. Experts are listed in each of the tumour specialties; digestive system tumours, breast tumours, soft tissue and bone tumours, female genital tumours, thoracic tumours. central nervous system tumours, paediatric tumours, urinary and male genital tumours, head and neck tumours, and endocrine and neuroendocrine tumours. [8]
The WHO started the project on the blue books in 1956. [9]
Leslie Sobin edited the first edition, published from 1967 to 1981, as the International Histological Classification of Tumors series. [9] [10] Sobin edited a second edition of 25 volumes, published by Springer between 1982 and 2002. [9]
In 1993 the WHO approved a concise classification of tumours affecting the central nervous system. [11] It was later revised in 2007 and then in 2016. [12]
The third edition of 10 volumes, was published in a new style as a series of World Health Organization Classification of Tumors from 2000 to 2005, and edited by Sobin and Paul Kleihues. [9] [10]
In 2006, the fourth edition was initiated and guided by series editors Fred Bosman, Elaine S. Jaffe, Sunil R. Lakhani, and Hiroko Ohgaki. It was completed in 2018 and included 12 volumes plus revised versions of central nervous system tumours and blood cancers. [9]
The fourth edition of the WHO Classification of Digestive System Tumors was published in 2010. [13] A fourth edition describing breast tumours was published in 2012, [14] Tumours of the Central Nervous System in 2017, [15] and the WHO Classification of Skin Tumors in 2018. [16] In it, the classification of melanoma is based on its mechanism and its association with sun-exposed skin. [16]
A fifth series was released in 2019, in a lighter blue and with a bold “5” on the book spine, to make it distinct from older outdated editions that might inadvertently be referred to. [3] The text appears in two columns; previously there were three. [3] It is the first in the series of the WHO blue books to appear online in its complete form, and includes a few books from the fourth series with the aim of updating books as they develop. [3] Its website uses images and hyperlinks. [7]
The first volume to be produced was on the classification of Digestive System Tumours. [17] Seven years after the fourth edition, a fifth edition on Soft Tissue and Bone Tumours was published in May 2020. [18] [19] The fifth Female Genital Tumours was published in September 2020. [20] [21] The fifth edition of Thoracic Tumours was discussed at the 2020 World Conference on Lung Cancer in Toronto. [22] It includes additional chapters “Diagnostic Molecular Pathology” and “Essential or Desirable Diagnostic Criteria”, and some new lung cancer types. [22]
The method of classifying tumours in the Blue Books was discussed in an accompanying article in the International Journal of Cancer in June 2020, titled "WHO Classification of Tumours: How should tumors be classified? Expert consensus, systematic reviews or both?" [6] [1] In it, they noted that heavy reliance on expert consensus relative to structured and controlled systematic reviews may result in bias, giving undue weight to particular literature or missing relevant studies. [6] In the first volume of the fifth series, 200 tumours or topics were marked as clinically irrelevant, and up to 130 were reported as “unknown”, with no further explanation of whether a detailed literature search was conducted. [6] Interpersonal and cultural factors, dominating characters, and the varying representations in each expert panel, influence decisions. [6] During updating, carrying forward previously incorrectly referenced material could also be a potential problem. [6]
The authors noted that biases are reduced somewhat by having an editorial board to oversee evidence and make decisions. [6] They questioned whether these problems could also be reduced by adding evidence‐based practices to the editorial process, but noted that imposing this might not be appropriate, and that some feel that "clinical judgment based on experience" has an importance that may not be emphasised from randomized controlled trials. [6] In conclusion, they proposed four “non‐negotiables” when carrying out literature reviews that affect important decisions for the WHO Blue Book series: transparency, searching rigor, double checking, risk of bias assessment. [1]
Invasive carcinoma of no special type, invasive breast carcinoma of no special type (IBC-NST), invasive ductal carcinoma (IDC), infiltrating ductal carcinoma (IDC) or invasive ductal carcinoma, not otherwise specified (NOS) is a disease. For international audiences this article will use "invasive carcinoma NST" because it is the preferred term of the World Health Organization (WHO).
Enchondroma is a type of benign bone tumor belonging to the group of cartilage tumors. There may be no symptoms, or it may present typically in the short tubular bones of the hands with a swelling, pain or pathological fracture.
Subungual exostosis is a type of non-cancerous bone tumor of the chondrogenic type, and consists of bone and cartilage. It usually projects from the upper surface of the big toe underlying the nailbed, giving rise to a painful swelling that destroys the nail. Subsequent ulceration and infection may occur.
A fibroepithelial neoplasm is a biphasic tumor. They consist of epithelial tissue, and stromal or mesenchymal tissue. They may be benign or malignant.
Appendix cancer, also known as appendiceal cancer, is a very rare malignant tumor that forms in the vermiform appendix.
Endometrial stromal tumours are a type of mesenchymal tumor of the main body of the uterus. Types include endometrial stromal nodule, the distinct low and high-grade endometrial stromal sarcomas, and undifferentiated uterine sarcoma.
An ameloblastic fibroma is a fibroma of the ameloblastic tissue, that is, an odontogenic tumor arising from the enamel organ or dental lamina. It may be either truly neoplastic or merely hamartomatous. In neoplastic cases, it may be labeled an ameloblastic fibrosarcoma in accord with the terminological distinction that reserves the word fibroma for benign tumors and assigns the word fibrosarcoma to malignant ones. It is more common in the first and second decades of life, when odontogenesis is ongoing, than in later decades. In 50% of cases an unerupted tooth is involved.
Cartilage tumors, also known as chondrogenic tumors, are a type of bone tumor that develop in cartilage, and are divided into non-cancerous, cancerous and intermediate locally aggressive types.
Germ cell neoplasia in situ (GCNIS) represents the precursor lesion for many types of testicular germ cell tumors.
A mixed tumor is a tumor that derives from multiple tissue types. A biplastic tumor or biphasic tumor has two tissue types.
The WHOclassification of tumours of the central nervous system is a World Health Organization Blue Book that defines, describes and classifies tumours of the central nervous system (CNS).
The giant-cell glioblastoma is a histological variant of glioblastoma, presenting a prevalence of bizarre, multinucleated giant cells.
The concept of grading of the tumors of the central nervous system, agreeing for such the regulation of the "progressiveness" of these neoplasias, dates back to 1926 and was introduced by P. Bailey and H. Cushing, in the elaboration of what turned out the first systematic classification of gliomas.
In the following, the grading systems present in the current literature are introduced. Then, through a table, the more relevant are compared.
A biphasic disease is a disease which has two distinct phases or components. In clinically biphasic diseases, the phases are generally chronologically separated. In histopathologically biphasic tumors, there is neoplastic tissue which contains two different cellular elements.
Pleomorphism is a term used in histology and cytopathology to describe variability in the size, shape and staining of cells and/or their nuclei. Several key determinants of cell and nuclear size, like ploidy and the regulation of cellular metabolism, are commonly disrupted in tumors. Therefore, cellular and nuclear pleomorphism is one of the earliest hallmarks of cancer progression and a feature characteristic of malignant neoplasms and dysplasia. Certain benign cell types may also exhibit pleomorphism, e.g. neuroendocrine cells, Arias-Stella reaction.
Thomas Grogan is an American professor, pathologist and founder of Ventana Medical Systems, Inc. He currently holds the positions of Professor of Pathology at the University of Arizona College of Medicine and Chief Scientific Officer at Ventana.
The colorectal adenoma is a benign glandular tumor of the colon and the rectum. It is a precursor lesion of the colorectal adenocarcinoma. They often manifest as colorectal polyps.
Bartholin gland carcinoma is a type of cancer of the vulva arising in the Bartholin gland. It typically presents with a painless mass at one side of the vaginal opening in a female of middle-age and older, and can appear similar to a Bartholin cyst. The mass may be big or small, may be deep under skin or appear nearer the surface with overlying ulceration. Average age at presentation is 53-years.
Poorly cohesive gastric carcinoma is a malignant tumour of epithelial origin, characterized by diffuse distribution of tumour cells, isolated from each other or in small groups.
Extraskeletal Ewing sarcoma (EES), is a cancer of soft tissue, a type of Ewing sarcoma that does not arise from bone.