PREVALENCE OF CNS TUMORS AND HISTOLOGICAL RECOGNITION IN THE OPERATED PATIENTS: 10 YEARS EXPERIENCE IN YEMEN

Background: Tumors of the central nervous system consist of a heterogeneous grouping of neoplasms of enormous histological variety. In spite of the increasing prevalence of CNS tumors in developing countries, certain places alike Yemen do not have representative studies showing the true impact of these tumors on the population. Aims: Description of the distinctiveness of primary and secondary tumors of the CNS in the past ten years in one Yemeni institute. Materials and methods: A descriptive-observational study was performed on patients with tumors of the CNS who were selectively treated by surgical excision with subsequent diagnosis through a study of pathological tissues at the Saudi German Hospital SGHSana'a, over a period of 10 years from January 1, 2009 to December 31, 2019. The variables of the study were qualitative (histological type, gender, affected anatomical position) and quantitative (age). Both group and histopathological diagnoses were formed in line with the 2006 WHO classification of CNS tumors. Results: There were a total of 359 central nervous system tumors. Of these, 200 were females and 159 were males, with a ratio of 1.3: 1 and a mean age of 49.3 years. The most common tumors were the neuroepithelium (28.4%), meningiomas (26.55%), followed by mesenchymal tumors (13.4%), sellar region tumors (11.14%) and the nerve sheets tumors (11.14%). Meningiomas had the highest prevalence in female patients (20.33%), while it was in male neuroepithelial tumors (15.32%). Single entity repeat point form, Grade I meningioma was the most common (18.11%) followed by pituitary adenomas (9.2%), Glioblastoma multiform (8.6%), Class II meningiomas (7.24%) and Schwannoma (6.7%). Conclusion: This is the firstly study of a sequence of cases in Yemen to be conducted on both benign and malignant tumors of the CNS, with all age groups patients with a extent of 10 years. Whilst this work represents no more than a retrospect ive analysis of a single institute, it can be a strong indicator of the epidemiology of the CNS tumors in Yemen.


INTRODUCTION
The tumors of central nervous system are a heterogeneous grouping of tumors of enormous histological variety and are restricted to the spinal cord, brain, meninges; and paraspinal and cranial nerves 1-3 . A large series was conducted by diverse groups allaround the world in order to verify the epidemiological and clinical features. It can be noticed in these studies that there has been a significant rise in latest decades, particularly in non-industrialized countries such as Yemen 1-5 . In some study series, these tumors are the leading cause of cancer-related death in children and draw attention to that more than 50% of children survivors of brain tumors have impaired cognitive function linked to the tumor or its treatment 5 . For that reason it is important to determine the recent features of these tumors in the environment. Nevertheless, in Yemen as in the majority of Arab countries, there are few specialized epidemiological records dedicated to this field, and for that reason it is important to encourage, update, build up and continue to offer studies on the manners of CNS tumors with the purpose of achieve a greater extent and influence on public health, with early diagnosis and suitable treatment with the purpose of enhance survival and reduce possible subsequent consequences.
The 6-year-old Saudi-Emirati aggression on Yemen has transformed this already weak country into the largest man-made humanitarian crisis in the world, taking away what its people need most, including basic needs, such as health care 6 . The United Nations report stated that in the year 2020-2021, more than 19.7 million people need health care services in Yemen, while only less than half of health facilities are still functioning. There are also about 1.5 million IDPs currently suffering from existing vulnerabilities including increased exposure to carcinogens 6 . According to the Limited Yemen Cancer Studies, the most common cancer among Yemeni children and adults were leukemia (33.1%), lymphoma (31.5%), central nervous system tumors (7.2%) and bone tumors (5.2%) 6-8 . This study was performed to give base line description of histopathological pattern of CNS tumors recorded in regional hospital SGH-Sana'a. These registers are not population-based cancer registration but is the only available source. Current study served to prove the basic demographic and histological data which can be competed with available studies on literatures. On other hand to provide primary base line tool to work-up for future population studies on CNS tumors.

PATIENTS AND METHOD
A descriptive observational study was performed in patients with CNS tumors that were treated selectively by surgical excision with succeeding diagnosis by studying pathological tissues at the Saudi German Hospital SGH -Sana'a, in excess of an interval of 10 years from first of January, 2009 to December 31. 2019. The study variables were qualitative (histological group, gender, affected anatomical site) and quantitative (age). Both group and histopathological diagnoses were formed in line with the 2007 WHO classification of nervous system tumors 9 . According to WHO classification, the patients were divided into 7 groups: neuroepithelial neoplasms, cranial nerve tumors, paraspinal tumors, tumors arising in the meninges, lymphomas, hematopoietic tumors, germinal cell tumors, sellar region, and metastatic tumors. We then classified subgroups according to morphological diversity. Inclusion criteria: Inclusion criteria included the histopathological diagnosis of primary brain tumor of any age and gender, availability of clinical data, and histological slides to confirm the diagnosis. Exclusion criteria: Exclusion criteria included no histopathological slides and insufficient clinical data. Statistical analysis Data were reported using appropriate descriptive statistics (including frequency, mean, standard deviation, and P-value). All statistical analyzes of the data were performed using the Statistical Package for Social Sciences (SPSS) version 24 and Excel 2007.

Ethical approval
The ethical approval was obtained from the Medical Research and Ethics Committee at the Faculty of Medicine and Health Sciences at Sana'a University with a reference number (202) dated 12-01-2021. Also, all data, including patient identification, have been kept confidential.

For age and gender distribution:
This study included 359 CNS tumors patients, 200 (55.7%) females with a mean age of 36.7 years, while 159 (44.3%) were male patients with a mean age of 39.5 years (Figure 1).

Figure 1: Sex distribution of CNS tumors.
Total 295 (82.2%) were adult patients aged 19-70 years with a mean age of 44 years ( Figure 2).

Frequency of CNS tumors with respect to gender:
Male patients showed a predominance in neuroepithelial tumors (15.3%) and sellar tumors (7.2%) while females showed a predominance over males in the other tumors except for NSTs were evenly distributed in both sexes (0.56% ) ( Figure 6).

Frequency of CNS tumours in relation adult age:
Meningiomas were the first common adult group  (Figure 7, Table 1). Frequency of CNS tumours in relation pediatric age ( Figure 8, Table 3): Gliomas were the first common tumours (42.2%) with predominance of astrocytomas 20 cases (74.1% of all Gliomas). Pilocytic astrocytoma was the commonest type of astrocytoma 14 cases (70% of all astrocytomas).   Prevalence rate of CNS tumours with site ( Figure 8 Figure 9, and Figure 10). Distribution of CNS tumours by grading in pediatric ( Figure 9,

DISCUSSION
Tumors of the CNS are one of the primary tumors in children and one of the most common causes for consulting neurosurgery services for adults. The endurance rate can be as deprived as 26% at 5 years for posterior fossa tumors and 7% when the brainstem is affected 10-12 . Neurocognitive sequelae are another major concern, primarily because of the managing of neurosurgery and the neurotoxicity of chemotherapy and radiation 13, 14   In the current study, Gliomas were the most common central nervous system tumors with 28.4% ( Figure 5).  In the current study, meningioma is predominantly a female cancer (20.33%) ( Figure 6). This is similar to studies conducted in Saudi Arabia 22-24 as well as the study reported by Adalberto Miranda-filo et al., 28 and it may be related to the high incidence of breast cancer among Yemeni patients 4 , confirming the hormonal effects that make females more susceptible to meningioma 29 . Astrocytomas was the second entity of individual neoplasms in adults after meningiomas in the current study, which represented 18

CONCLUSION
This is the firstly study of a sequence in Yemen looking at CNS tumors, which includes patients of all age groups over a period of 10 years. Even though this study is no more than a retrospective analysis of a single institution, it can be a strong indicator of the epidemiology of CNS tumors in Yemen. In addition, the current study recorded data matches with those in the global literature and neighboring country studies, with some differences.