INTRODUCTION
A recent report on cancers showed that cancers of the oral cavity, pharynx and salivary glands are responsible for an estimated 390,000 (3.9% of total) new cases of cancer worldwide in 2000 1.
In Africa, the frequency of these cancers is lower, with an estimated 19,500 new cases in 2000, representing 3.1% of new cancers.
The report also showed a great deal of geographical variations in the incidence of oral cancers. High incidences were reported in regions where it is related to factors like tobacco in the Indian subcontinent, Papua New Guinea and Sudan, and alcohol in France, Switzerland and Eastern Europe 1. Acquired Immune Deficiency Syndrome (AIDS)-related cancers of the oral cavity (kaposi sarcoma and non-hodgkin?s lymphoma) with prevalence ranging between 0-12 % have also been reported in various studies in Africa since the advent of the disease world-wide 2. The relative distribution of sites within the oral cavity also showed considerable differences. Lip carcinoma was associated with whites in areas of high UV radiation; carcinoma of the gums, floor of the mouth and vestibule in tobacco chewers, snuff dippers and toomback users 1,3,4. Odukoya and others, in a study demonstrated the role of kolanuts in promoting the cigarette smoking-induced keratinization of human palatal mucosa 5.
Different studies on oral cancers in Nigeria have reported a relatively low incidence of the condition. This observation has been variously attributed to the low dentist: population ratio, poor and inadequate hospital services and a poor (and almost non-existent) cancer registry records obtainable in Nigeria 6,7. The inception of such services in 1987 at the Jos University Teaching Hospital, Jos serving the North Central zone is expected to improve the reporting of oral cancers from this zone. The zone also recorded the highest rate of HIV sero-positivity (9.86%) in Nigeria in a national survey between 1989 and 1990 8.
This study was carried out to document baseline information on the epidemiological pattern of oral cancers (ICD-O: C00-C06) in this multi-ethnic region of Nigeria.
MATERIALS AND METHODS
The ethical clearance required to access data for the study was obtained from the Chief Medical Director of the hospital.
Socio-demographic information and history of patient management (age, sex, occupation, ethnic group, history of habits; history of symptoms, dates of referral and first appointment, pre-treatment and histological TNM staging of lesion, clinical and histological diagnoses, dates of biopsy and dates of biopsy report; definitive treatments and date of discharge) according to the pattern developed for the Minimum Cancer Dataset9 by the British Association of Head and Neck Oncologists (BAHNO) were retrieved from pathology records and medical records of patients diagnosed histologically of cancers of the oral cavity (M-8000/3) at the Jos University Teaching Hospital, Jos for the period between the start of histopathology services in January 1987 till December 2002.
The oral cavity, for the purpose of this study, includes the lip (excluding the skin), tongue, gingiva, floor of the mouth, buccal mucosa, alveolus of maxilla and mandible, unspecified "mouth"/ "oral cavity" and the palate, as classified by the International Classification of Diseases for Oncology (ICD-O: C00-C06) 3rd Edition 10.
The information was analyzed statistically using the SPSS statistical package (Version 11+) and Epi Info Version 6.0. Relationships between nominal variables were calculated using the Chi square (Fischer?s Exact) Test. The Kolmogorov-Smirnov Test was used to test association between various habits and oral cancers. A p-value of 0.05 or less was considered significant.