Risk factors of Oesophageal Cancer in South Africa

Abstract

Oesophageal cancer is one of the most fatal cancers worldwide with a five-year survival below 15%. The incidence, histology and aetiology of oesophageal cancer vary remarkably between and within countries as well as between ethnic groups. In South Africa the disease affects mainly African males and the highest incidence of oesophageal cancer occurs in the Transkei region of the Eastern Cape. Risk factors that have been reported to play a predominant role in the aetiology of oesophageal cancer include chronic irritation to the oesophageal mucosa, poverty, nutritional deficiencies, Human papillomavirus (HPV) infections, alcohol and smoking. However, none of them seem to singularly account for the high incidence rates observed in several high-risk areas as well as the dramatic variations in the frequency of oesophageal cancer in distinct geographic areas. Infection by human papillomaviruses was first implicated in the aetiology of oesophageal cancer in 1982. We have demonstrated the presence of low-risk HPV type 11 in subjects with squamous cell carcinoma of the oesophagus as well as subjects with dysplasia from South Africa. The E6 proteins of high-risk HPV contribute to tumorigenesis by interacting with wild type p53 and induce its degradation. However, HPV type 11 is known to bind to the p53 - carboxyl terminus without inducing its degradation.