DISCUSSION

The results of this study cannot be compared with findings in the previous study conducted in Jos because of the non-standardization of the inclusion and exclusion criteria for cancers in that study.

The prevalence of cancers of the tongue is about 2-4 times higher (p=0.0047) than the 8.3% and 14.6% reported in Maiduguri and Zaria respectively, while the prevalence of palatal cancers is lower than the 32.2% and 39.6% (p>0.05) observed in Zaria and Maiduguri respectively ¹². Alcohol and smoking have been associated with carcinomas of the tongue and palate respectively ¹. The common occurrence of the habit of chewing kola nuts among oral cancer patients in the north east and north west of Nigeria had earlier been reported. A co-carcinogenic role of kolanuts in tobacco smokers has been suggested ^5,13.

Alcohol has been shown to reduce the anti-oxidant capacity of abusers ¹⁴. Alcoholic beverages commonly consumed in the area of the study are processed locally from guinea corn and millet, during which there is a substantial loss of the ?trace amounts? of essential anti-carcinogenic nutrients like β-carotene, vitamins A, C& E, which have protective roles in carcinogenesis ^14,15,16.

Cancers in "unspecified mouth" constituted 9.3% of oral cancers. This high level could be attributed to the extension of the lesion in its advanced stage before reporting to the hospital⁷. The non-availability of the dental or maxillofacial specialty in the hospital could also contribute to the high level of inaccuracy in the identification of affected cancer sites.

Relative to cancers of other sites, palatal cancers showed the least age of occurrence in this study. This could be attributed to the biological characteristics of the prevalent rhabdomyosarcomas in this site ¹⁷. The prevalence of oral cancers in patients aged 40 years and below is significantly higher (p<0.05) than reported in the USA ¹³. The AIDS-related oral cancers observed in this study, kaposi sarcoma and non-hodgkin?s lymphoma, agrees with previously reported African studies ².

In a prospective study of oral manifestations of HIV/AIDS in Jos, nine cases of kaposi sarcoma were recorded in seven months in 2003, showing an approximately 8-fold increase in the occurrence of AIDS-related cancers over the previous years ¹⁸. This is an indication of the high and rising prevalence of confirmed HIV cases in the North Central zone, with an increasing transformation into full-blown AIDS and its associated oral manifestations ⁸. The advent of this disease, with its characteristic role in immunodeficiency, may enhance the progression of carcinogenesis in patients.

The early reporting of the cancers of the tongue, along with the late stage at presentation, could be attributed to the loss of function and pain associated with the spread, fixation and neural involvement of cancers of this site. The delayed reporting and advanced stage at presentation is as reported for previous studies in Nigeria, but contrasts with the 10-15% or less of patients with cervical metastasis at presentation reported in the USA ^4,7,13,19. The late presentation, coupled with the observation that majority (70.6%) of the patients did not have prescribed treatments could be attributed to the delay in diagnosis arising from the non-availability of dentists who would perform routine oral cancer screening of patients seen in the hospital, poor access to hospitals and the primary recourse to traditional medicine ^20,21.