Epidemiology Of Oral Kaposi’s Sarcoma In Zimbabwe 1988-1997: A Population-based Study

Abstract

Objective: To date, no study has investigated the incidence of oral Kaposi’s sarcoma (OKS) in African populations affected by the human immunodeficiency virus (HIV) and the Acquired ImmunoDeficiency Syndrome AIDS epidemic. It is, therefore, the purpose of this study to assess the burden of OKS in the Zimbabwean population over a ten-year period.
Design: A descriptive epidemiological study was undertaken to assess the burden of OKS by determining the frequencies, incidence and cumulative rates, the lifetime risk and odds of developing OKS according to site (topography), gender, age, race/ethnic origin of the Zimbabwean population. Incident cases of OKS from the upper and lower lips, oral vestibule, retromolar area, floor of mouth, tongue, cheek mucosa, gums, hard and soft palate were accessed from the Zimbabwe National Cancer Registry (ZNCR). Cases from the skin, pharynx, larynx and the major salivary glands were excluded from the study.
Setting: This comprised the population of Zimbabwe during a ten-year period 1988 to 1997 using population figures from the 1992 Census Zimbabwe National Report. The study population was standardised by the direct method against the world standard population to calculate the age standardized incidence rate (ASIR). The SPSS statistical software program (SPSS Inc.2001, USA) was used for the statistical analysis.
Results: OKS comprised 0.92% of total body malignancies and 51% of oral malignancies with a mean age of study cases of 37.6 years and median age of 32 years. Histology of the primary (64.5%) and clinical diagnosis (34.6%) were the predominant methods of diagnosis. OKS affected almost exclusively blacks and males more than females with a male to female ratio of 1.9:1. The most affected age groups by OKS were the 30-34 for males and 25-29 for both females and the whole population. OKS mostly affected the palate (70,2%) followed by, in descending order, the tongue (13.3%) and mouth (8.3%). The age adjusted age standardised incidence rate (ASIR) of OKS exponentially increased the entire study period surpassing oral squamous cell carcinoma (OSCC) as the predominant oral malignancy in 1994.
Conclusions: OKS was the commonest malignancy of young adults affecting males more than females and surpassed oral squamous cell carcinoma in 1994 to become the commonest oral malignancy for the remainder of the study period. The palate was the most affected intraoral site by OKS. The possibility of human herpes virus 8 being HIV strain-specific in the aetiopathogenesis of oral Kaposi’s sarcoma warrants further investigation. 

Keywords: Oral Kaposi’s Sarcoma, palate, incidence rate, lifetime risk, human herpes virus 8