106 T. GlLLMAN 



South Africa and elsewhere. For example, the incidence of 

 carcinoma is considerably lower in the African; but, when 

 carcinoma does occur, as Dr. Charles Berman has shown so 

 clearly (1951), about 90 per cent of cancers in African males 

 are cancers arising primarily from hepatic epithelium. But 

 this is probably already well known to many of you. I think 

 that Dr. Muhlbock's remarks may have some significance 

 for the understanding of this peculiar carcinoma incidence. 

 Dr. Muhlbock observed that many of his mice that have 

 apparently a lethal gene, and die early, do not get carcinoma. 

 This low, but peculiar, carcinoma incidence in the African male 

 may be due to several things. One may be the fact that the 

 African just does not seem to live long enough to develop the 

 other types of cancers so common among Europeans. After 

 all, certain biological reactions, once initiated, seem to require 

 fairly fixed times for their completion, e.g. the action of insulin 

 or of oestrogen in certain specified physiological circumstances, 

 as well as the time required for the production of certain types 

 of carcinomas, such as the lung cancers which we have found 

 to follow the application of methylcholanthrene to the skin 

 (Gillman, Hathorn and Penn, 1956). Perhaps this biological 

 peculiarity may, in part, explain the low incidence of non- 

 hepatic cancers in Africans. 



However, there may perhaps be other reasons for this 

 peculiar cancer incidence in the African, and we have tried to 

 find something in the African which would account for this 

 peculiar cancer incidence. In so doing we came across a 

 number of other unusual reactions which we feel have a 

 common basis. Among them is the fact that the African 

 liver is severely injured, with great frequency and on repeated 

 occasions, virtually from birth. The nature of the hepatic 

 reactions in Africans, as my brother and I have already 

 described (Gillman and Gillman, 1948, 1951), varies at differ- 

 ent ages. 



Although I was accustomed to seeing a considerable amount 

 of liver disease in Johannesburg, I have been shocked by the 

 apparently even higher incidence in Durban Africans. In a 



