New Histopathological Diagnostic Terms and their Codes of the Central Nervous System (CNS) in the International Classification of Diseases for Oncology (ICD-O 3.1) and about the Turkish Version of ICD-O

International Classification of Diseases for Oncology (ICD-O), which has been used in the world since 1976 for 40 years and has been translated into many languages, emphasizing the importance of health and cancer is presented. In addition, the histopathological classification working group of central nervous system (CNS) tumors has proposed new terms and their new ICD-O codes, taking into account their genetic characteristics. Our goal is to emphasize the current importance of ICD-O. Since 2015, ICD-O has been put into practice by the Ministry of Health in Turkey. Writing of ICD-O codes is required for pathology reports. In the last 25 years, I have translated the ICD-O three times into Turkish, 1992, 2002 and 2015, serving as pathology, oncology, cancer registrars and the Ministry of Health.


Introduction
The International Classification of Diseases for Oncology (ICD-O) has been used for nearly 40 years as a standard tool for coding the site and the histology of the diagnostic terms of the neoplasms in tumor and cancer registrars and in pathology departments and pathology laboratories, usually obtained from a pathology report [1][2][3][4].
The ICD-O is the gateway to the world that the latest information has been freely available to entire world's people so that World Health Organization's (WHO) diagnosis and treatment of health and cancer in the world can be made at the highest level of knowledge and scientific benefit.
ICD-O is a dual classification with coding systems for both topography and morphology.
The topography code describes the localization of the tumor and uses the same 3-character and 4-character categories as in the neoplasm section of Chapter II, ICD-10 [5].
The morphology or histopathology code describes the features of the tumor itself, including its cell type and biologic activity and genetic properties.
In preparing the revised edition of the ICD-O 3.1, the editors have made a special effort to change as few terms as possible, to add new terms at empty spaces, and to avoid reuse of previously assigned codes [4]. While all topography or localization codes remain the same as in the previous edition, morphology or histopathology codes have been thoroughly reviewed and, where necessary, revised to increase their diagnostic precision and prognostic value [4].
Currently, in the light of new scientific and technological developments, especially genetic features and characteristics have become very important element in tumor diagnosis.
On the other hand, if we look at new information, new technological improvement and new perspectives, the use of the international histopathological classification of tumors and neoplastic diseases has become a compulsory rule to use in pathology in the all over the world. So, this approach is to promote the adoption of a uniform terminology that will facilitate communication and dialog among cancer workers.
As a matter of fact, in the light of new information and scientific developments, the importance of ICD-O 3.1 for this reason it has increased more. Therefore ICD-O books translated many languages around the World including Turkish. I have been working on the Turkish version of ICD-O for the past 25 years since 1991 as reported by Fidaner C et al. [6] and as reported by Eser S et al. [7] and I am very happy to prepare the Turkish version of ICD-O 2, ICD-O 3 and ICD-O 3.1 during this time [8][9][10] (Figures 1-3).
These studies have been made to provide scientific and social benefits as a volunteer and with the sensitivity of a non-profit scientist. Our aim is to get scientific and social benefit in the field of pathology, oncology and cancer registry, besides community health, especially in the fight against cancer in Turkey.  The decision of the Ministry of Health to implement ICD-O in all health institutions and pathology reports is a valuable and up-to-date scientific development that at the same time opens the door to new scientific and social studies as much as possible to make respectable and scientific cancer statistics in Turkey.
Also, the result of new scientific and technological developments, especially in the following areas, new terms have emerged; Central nervous system (CNS) [11], hematopoietic and lymphoid tissues [12], digestive system [13], breast [14] and urinary system [15] tumors and so on. In this review new terms and ICD-O codes related to CNS tumors will be presented.
Our aim is to emphasize newly identified tumors, terms and codes in CNS tumors which is seen in the ICD-O 3.1 and to explain as a briefly the progress made about in the use of ICD-O and the Turkish version of ICD-O in Turkey.

New and Changing Terms of the CNS, and their Codes in ICD-O 3.1
ICD-O 3.1 includes new terms, changing terms, and new codes related to CNS tumors, as in other areas. In particular, the increase in the demand for genetic tests related to histopathology diagnoses and the presence of new technologies make it mandatory [4].
In addition, these new developments and new histopathologic diagnoses make better results on the treatment and prognosis of the disease.
Significant changes have been made in the codes and terms of CNS tumors under the influence of new techniques in use in current histopathology.
Accordingly, ICD-O 3.1 includes new diagnostic and terminology changes as well as concerns about biological behavior changes. These changes have affected the studies related to neuropathology, neurosurgery, neuro-oncology, neuroradiology and neuro-nuclear medicine and have caused many changes in terms of patients in practice.
Therefore, all these new and very important changes specific to CNS tumors, taking advantage of the tables of tumors of all systems in the ICD-O 3.1 original book, as shown below, I also tried to summarize them in tables form [3,4,9,10] (Tables 1-7 (10).

Conclusion
In the ICD-O 3.1 edition, new histopathologic markers and genetic information were taken into consideration in the new classification of CNS tumors in the field of neuropathology, resulting in the following new developments [4,9,10]: • New codes, • New morphology terms and synonyms, • Terms that changed morphology code, • Terms that changed from tumor-like lesions to neoplasms, • Terms which were deleted, • Terms that changed behavior code, • New codes, preferred terms, related terms, and synonyms.
Under the influence of the contemporary scientific and technological improvement, the histopathological diagnosis of the patients becomes more realistic, also directs the treatment and have an effect on the prognosis. Because under these new circumstances, for example, the result of extraordinary innovations on genetics [16][17][18] and PET (positron emission tomography) pharmaceuticals [19][20][21], on the near future, new kind of tumor histopathologic diagnoses can be predicted, so new approaches of pathologists and oncologists will be seen.
These new diagnostic terms and codes mentioned are also important in influencing the patient's prognosis and treatment strategy. For this reason, it should be taken carefully into consideration.
In this study, attention was drawn to new terms, codes and improvement related to CNS tumors, which constitute a special group of human tumors, emphasizing and presenting the importance At the same time, WHO's ICD-O and Tumor Classification Books and pathological, oncological and coding studies in parallel with these principles is to present comparable data on cancer incidence for all countries around the world for which high-quality data have been made available by population-based cancer registries [22].
As a result, in line with WHO's work, it is a good step for the Ministry of Health to put the ICD-O codes into practice in all hospitals and healthcare facilities, starting in 2015 (2014) in Turkey [23,24].
Similarly, the definition of Pathology reports according to current WHO Tumor Classifications and coding with ICD-O codes is very important and valuable for Turkey in terms of scientific prestige as well as the health and prognosis of patients.