CHAPTER 1: INTRODUCTION

1.1. Background

Brain tumours are reputed for their poor prognosis. This is most at times due to late diagnosis prompted by the challenges in its diagnosis especially in our context (1). It is however a scenario that healthcare givers especially neurosurgeons and pathologists don’t tend to see every other day in our context due to the relative paucity of cases (2–6). An initial multicentric study on this pathology between 1996 and 2006 revealed important insights on the pathology from a multicentric standpoints with 6.3% of neurosurgery hospitalisations accounted for by tumours of the CNS (1,7). We seek to bridge the gap in time, place and knowledge by complementing this data with up-to-date data and including centres which were not studied before.

A tumour is an abnormal growth of tissue, and that can happen anywhere in the body. According to Fonkem et al., a brain tumour or intracranial tumour is an abnormal mass of tissue where cells grow uncontrollably and unaffected by typical cell regulatory systems within the brain parenchyma or its coverings (8). In the central nervous system  (CNS), the most commonly affected organ is the brain, accounting for over 84% of CNS tumours (9). They could be primary tumours or metastatic tumours as described by Djientcheu et al. in Yaounde (10).

There is a marked difference between findings in the developed world compared to those in the developing world, with a fivefold spike in the findings of the developed world, particularly in Europe (11). There has over the past decades been a rising incidence of these cases (4,9,12), hence the pressing need for current and up-to-date data on its diagnosis and management. Discussing the epidemiology of brain tumours is better done according to groups  (age, sex, or ethnicity) than as a bulk  (9).  Primary tumours are more common in the paediatric age group whilst secondary or metastatic tumours predominate in the adult population (10,13). Most paediatric brain tumours occur in the posterior fossa and are the second most common in this age group (3,12,14), while those of the adult population occur in the supratentorial space (7).

Brain tumours are classified based on their histology, which refers to the microscopic structure of the tumour cells. Neuroepithelial tumours arise from the brain’s own tissue and include astrocytomas, oligodendrogliomas, and ependymomas, while Non-neuroepithelial tumours include meningiomas, schwannomas, and germ cell tumours (1,15). Tumours could be primary or secondary. Primary brain tumours develop from tissues within the cranial cavity. They could be benign or malignant. The term benign is used to describe a slow-growing, histologically well-differentiated mass (15). Malignant brain tumours are abnormal cell growth with the potential to invade or spread to other parts of the body (15). On the other hand, secondary brain tumours which are usually metastasis from other body parts (10,13). However other parameters need to be considered when discussing such tumours within the brain. The brain unlike other organs is enclosed within a rigid bony framework in an adult, hence permitting for very little growth or accumulation of mass or fluid. Also, this noble organ has very sensitive highly specialized areas which if tempered with even within the scale of micrometres could engender serious deleterious effects to the rest of the body. Therefore, mindful of these, a benign tumour in the brain could be as dangerous as a malignant tumour within the brain  (12).

The evidence needed to make a diagnosis of brain tumours range from subjective to objective, from clinical through radiological to pathological (7). Clinical clues such as past medical and family history with a careful search for risk factors  (11), patient symptomatology, and physical examination orient toward the diagnosis. This is further confirmed with a magnetic resonance imaging  (MRI) technique which is the gold standard and histopathologic studies to confirm the type of tumour. However, in our study setting, all of these facilities are not often available or come with a lot of delay. Clinicians despite this challenge have to continue management and have to discuss the pathology with the patient and caregivers. It remains a challenge to both parties in our study setting.

The management of this pathology is primarily surgical (3). However, the management entails the involvement of a multidisciplinary team medical or targeted therapies could be initiated in certain circumstances. A study on the management algorithm of brain tumours in Cameroon by Djientcheu et al. designed a decision tree where in after brain imaging, surgery is given priority, then is histological studies which will orient the clinician on the need for adjuvant treatment modalities such as chemotherapy or radiotherapy (2). But for the sake of the scope of this work, these will not be overemphasized.

This study therefore aims to evaluate the frequency, types, and risk factors of brain tumours in Cameroon, with particular attention to the diagnostic modalities displayed here.

1.2. Problem Statement

Secular  trends reveal an increase incidence of brain tumours globally (4,11,12). There is marked paucity of data in sub-Saharan Africa (4), Cameroon inclusive with most studies done in Yaoundé and Douala with no data yet from the new neurosurgery centers at the periphery. Furthermore, diagnostic facilities are concentrated in at the central level. This makes the diagnosis at the peripheries difficult hence the need for this study.

There is, therefore, an imminent need to engage in more studies in this area of subspecialty to generate original data tailored to our microecology to guide our policy-making system and evidence-based medical protocols.

1.3. Justification

Epidemiologic: there is paucity of data on this pathology. As such, the limited notion the epidemiologic trends on the pathology in our setting. The pioneer study done on Brain tumours in Cameroon by Bassong et al. was over 15 years. We seek to update this knowledge with findings in this era and complement with data from the periphery as this study included centers in Yaoundé and Douala. These elements prompt us to further study this study in multiple centres in order to have a broader picture on the epidemiology of this pathology.

Contextual: Diagnostic facilities needed for the management of brain tumours are concentrated in the major cities. This makes the diagnosis and management in the peripheral regions difficult. As such, we set out to study the diagnostic aspects of this pathology in these remote parts of the country.

Further research: Our study intends to conglomerate data from the hinterlands where there is at least the service of a neurosurgeon and/or pathologist to produce a synthetic profile of brain tumour diagnostic aspects nationwide. This will complement existing data to give a complete profile of brain tumours on the national territory.

Health Care planning: There is need for original data tailored to the realities and needs in our community. As such, our study will provide such information. This information will be important to guide policy on the allocation or resources and the reform of policies in this subspeciality of interest.

Summarily, study will first establish an epidemiologic profile in our country, and uncover the various diagnostic techniques available to clinicians to permit faster and more accurate diagnostic steps in front of brain tumour cases. Our study therefore is vital in advocating for prompt and accurate diagnosis of brain tumours, and eventually safe, available, affordable, and quality management wherever and whenever the need arises.

1.4. Research Goal

Our goal is to assess the epidemiology, clinical, radiologic and histopathologic diagnostic aspects of brain tumours in five centres in Cameroon.

1.5. Research Question

• What is the prevalence of brain tumours among neurosurgery hospitalisations?
• What are the common clinical features of patients presenting with brain tumours?
• What are the Radiologic features of brain tumours?
• What are the various histologic subtypes of brain tumours encountered?

1.6. Research Hypothesis

Null hypothesis: clinical, radiologic and histopathologic diagnosis is not available for all patients diagnosed with brain tumours in Cameroon.

1.7. Research Scope

We systematically reviewed clinic charts, laboratory reports, and radiologic data for all patients in the surgery/neurosurgery units and pathology units of chosen hospitals From April 1^st, 2019- April 31st, 2024.

1.8. Research Objectives

1.8.1. General objective

• To access the epidemiology, clinical, radiologic and histopathologic diagnostic aspects of brain tumours in five centres in Cameroon.

1.8.2. Specific Objectives

1. To determine the prevalence of brain tumours among neurosurgery hospitalisations.
2. To describe the common clinical features of patients presenting with brain tumours.
3. To enlist the radiologic features of brain tumours diagnosed in Cameroon.
4. To elucidate the various histologic subtypes of brain tumours within our setting.