The cancer pattern in Africans of the Transvaal lowveld.

An attempt has been made to study the Transvaal lowveld by district and tribe in relation to cancer patterns, and to compare these with those of bordering regions.The lowveld is divided into four districts, running from north to south. There appears to be a real increase in the frequency of liver and bladder cancers from north to south. The low cancer measurements in the most northern district (Letaba) are probably due to low cancer susceptibility. When cancers appear more common in the north, this is of interest seen against the very low cancer rates there. Both skin and musculo-skeletal tumours were commoner in the two northern districts in the ratio study and this was to some extent still true in the crude rate estimations.Tribally, the Sothos predominate in the north, the Swazis in the south, the Shangaans are evenly distributed through the area. It appears that Sothos are less cancer-susceptible than the other tribes. Looking at geographic and tribal differences together it would seem that liver cancer is related to physical environment whereas bladder cancer is associated with tribe.An attempt to compare contiguous areas is made in a ratio study comparison between highveld, lowveld and Lourenco Marques. Standardised cancer morbidity incidence rates from three surveys: Lowveld (1962-67), Johannesburg (1953-55), and Lourenco Marques (1956-61) are also compared. Generally speaking, the lowveld occupies a mid-position, both geographically and in terms of cancer patterns, between Lourenco Marques and the highveld-Johannesburg area.