Mesothelioma in South Africa, 1976-84: incidence and case characteristics.

Malignant mesothelioma is a rare tumour known to be associated with prior exposure to asbestos. Previous studies have described the occupational and clinical features of cases of mesothelioma in the Republic of South Africa (RSA) but none has set out to determine incidence of this disease. To estimate incidence, a case register was compiled for 1976-84 by contacting all medical practitioners and institutions likely to have seen cases of mesothelioma in this period; demographic, diagnostic and exposure details were sought. Cases were accepted if they provided evidence of histological diagnosis of mesothelioma. Fifty-two per cent of 1347 cases identified were in whites, 31% in blacks, 16% in coloureds and 1% in Asians. Seventy-three per cent of cases occurred in males. The majority of whites were aged 51-70 years, while the majority in other race groups were aged 41-60 years. The ratio of only pleural to only peritoneal mesothelioma was 11:1, although there were marked differences by race. Eighty-five per cent of males with exposure information available had prior exposure to asbestos, mostly occupational. A similar proportion of women had contact with asbestos but mostly through other types of exposure. Standardized incidence rates per million population aged 15 years and over were calculated for sex-race subgroups and were highest in white males (32.9 per million per year, 95% Cl 22.7-46.4), coloured males (24.8 per million per year, 95% Cl 16.2-36.9) and coloured females (13.9 per million per year, 95% Cl 7.7-23.5). These incidence rates are amongst the highest ever reported for a national population. Age-specific standardized incidence rates were highest in white males (over 100 per million per year in men over 55 years). Reasons for the differing rates by population group are likely to include differential access to health services. More rigorous control of asbestos exposure in the RSA is recommended.

Lung cancer cell type and mining exposure.

It is frequently stated that the most common primary lung cancer cell type in asbestos-exposed persons is adenocarcinoma. Recently a contrary opinion has been expressed. This study compares the cell types recorded among deceased South African miners whose lungs were examined at the National Centre for Occupational Health. It supports the opinion that adenocarcinoma is not associated with asbestos exposure. From the large database available, there is no evidence of a consistent association between any particular cell type and specific mining exposure.