CANCER RESEARCH 23 



Sometimes we find the statement made that cancer is more frequent 

 among the well to do than among the poor. It is doubtful whether this 

 statement is correct. Some recent statistics point rather to the reverse. 

 Again there seems to be in this respect some difference in the various 

 kinds of cancer. Cancer of the cervix of the uterus appears to be more 

 frequent among the poor, while mammary cancer is perhaps more fre- 

 quent among the well to do. 



There exists no marked difference in the incidence of cancer in 

 country and city. On the whole, we are apt to find a somewhat greater 

 incidence of cancer in the cities, especially in parts of the world where 

 the number of physicians per unit of population is considerably smaller 

 in the country and where therefore in all probability the number of un- 

 recognized cases of cancer is greater in the country. The difference is 

 therefore probably rather apparent than real. 



There have been noted in various countries certain areas where 

 cancer appeared to be more frequent than in others. Some observers 

 believed especially damp-wooded country to be favorable to the develop- 

 ment of cancer. Some physicians recognized certain houses or streets 

 in villages or small towns, where the incidence of cancer was especially 

 great. Behla for instance reported such an occurrence in the small 

 Pommeranian town Luckau. These observers declared cancer to be 

 " endemic " in certain localities and were often inclined to attribute this 

 localized increased frequency to unknown infectious agencies. Although 

 it is very difficult to interpret these observations, it does at present not 

 appear probable that they ought to be referred to infection. Such can- 

 cer houses have been found only rarely: the number of cancers that 

 occurred in these houses were relatively few, and furthermore cancer 

 occurred also in the neighboring districts. Neither can we exclude the 

 possibility that hereditary factors played a part in some of these cases. 

 There is, however, no doubt that in certain parts of various countries 

 cancer is more frequent than in others. 



So far we have considered the incidence of cancer mainly among the 

 white population of Europe and America. The incidence of cancer 

 among certain races living under more primitive conditions is quite 

 different. Among the negroes of Africa cancer is much rarer than 

 among the whites of Europe and America. Although according to von 

 Hansemann the same varieties of cancer occur there as in civilized 

 countries, the proportion of the various kinds of cancers differs 

 markedly. We find among the African negroes relatively frequently 

 benign tumors of the connective tissue group as for instance lipomata 

 (fat tumors). Sarcomata are correspondingly much more frequent 

 than among the Europeans and it is furthermore very probable that the 

 relative frequency of the various kinds of carcinomata is different^"" 

 Also among the Arabs of Algiers sarcoma is more common than Cj&y^os 



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