Significant decline of hepatocellular carcinoma from 1964 to 1996 in black gold miners from Mozambique working in South Africa

Exceedingly high rates of hepatocellular carcinoma (HCC) have long been reported among both the resident male and female populations of Mozambique and among the all-male migrant labour force from that territory who work on the gold mines of South Africa. Medical records of the Chamber of Mines and labour records of The Employment Bureau of Africa, analysed for HCC over a 33-year period, show a regular decrease of HCC in miners recruited from Mozambique, from 78.1 cases per 100 000 man-years in the first period, 1964-68, to 16.9 in the latest quarter, 1989-96. A similar change is reported among the resident population. In both groups the epicentre of HCC lies in the east of the country in inhambane province. By contrast, low cancer rates among Mozambican miners in the period 1989-96 are recorded for several sites, especially those related to HIV/AIDS. The substantial and unexplained decline of HCC is considered in relation to the severe hardships of environmental conditions and to postulated changes in life expectancy from prolonged wars, HIV/AIDS and other infections, as well as ingestion of food-borne aflatoxin or changing status of HBV infection.