Liver cancer prevention in The Gambia, West Africa.

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In The Gambia, liver cancer is the commonest form of cancer among males and the second commonest in females. The age-adjusted rates are: 34 per 100,000 and 11 per 100, 000 in males and females respectively. Such results puts this small west African state among the areas with the highest morbidity and mortality for HCC by global or regional or national standards. The commonest histological type of liver cancer in sub-Saharan Africa is hepatocellular carcinoma and the association of this disease with persistent infection with Hepatitis B virus (HBV) and or Aflatoxin or Hepatitis C virus (HCV) is common knowledge. In fact there is hardly now any dispute among Epidemiologist that HBV causes HCC. Population attributable risks of 60-80% were recorded in Sub-Saharan Africa and elsewhere. In The Gambia, Epidemiological studies, mainly, case-control studies showed that HBV infection is universal and chronic carriage of the virus, the main risk factor for HCC, is in the range of 15-20%. This classifies the country among the highly endemic areas for HBV infection. Exposure to dietary Aflatoxin is also high. Dietary surveys during the late eighties revealed levels of beyond 100 ng/kg bw/day among the rural and urban populations. Infection with HCV is below 3% among the general population and even less so among the under 50 age categories. Since 1986 a model public health strategy to combat HBV infection and HCC in The Gambia was initiated as a collaborative undertaking between The Gambian Government (GG), the International Agency for Research on Cancer (IARC) and the Medical Research Council of the United Kingdom (MRC). This strategy denoted The Gambia Hepatitis Intervention Study (GHIS) can be described as a Randomised Control Trial integrated into policy. The main expected outcome of the strategy was a significant reduction in the rate of infection of HBV during the short term, followed by a significant reduction in the incidence of HCC in the long-term, among this high risk population. Currently results show that, vaccination against HBV in The Gambia, during the first year of life is more than 80% and >90% effective against HBV infection and chronic carriage, respectively. To what level these achievements translate into reduction in the incidence of HCC remains to be seen. The GHIS strategy was based on a series of assumptions which have been assessed again using the information collected over 17 years into the programme. This presentation will present material on the current status of the GHIS strategy and also present and discuss its various assumptions in the context of the information collected during 17 years of operation.