Abstract
The primary causes of cancer are still unknown. It seems, however, more and more evident that the development of cancer is particularly favoured by certain conditions, viz. chronic local irritants and old age.
The chronic local irritants are of the most variegated descriptions, belonging to all manifestations of energy—mechanic, thermic, chemical, radiological; there are also vital (animal) irritants (Bilharzia, Spiroptera neoplastica s. Gongylonema neoplasticum, Fibiger), and pathological irritants (precancerous conditions).
But the very difference in the nature of all these irritants indicates that it is scarcely the irritants themselves but more likely the reaction of the organism against these, which offers the conditions favourable for the development of cancer. Borrmann and Ribbert emphasize that, previous to the cancerous proliferation of the epithelium there is constantly found an inflammatory alteration of the underlying connective tissue, representing an alteration of the conditions of life of the epithelial cells.
Very frequently, though, cancer develops in localities where no irritants or irritation have been noticed.
The influence of age is more obvious; statistics from all countries here agree. In Norway, the mortality from malignant tumors, for the years 1901–1915 is shown in table 1.
Of these 32,274 deaths from malignant tumors, only 206, or 0.64 per cent, have occurred in persons under thirty years of age; only 1146, or 3.55 per cent, under forty years, though these groups include 59.27 per cent and 71 per cent respectively of the whole population.
- Received June 2, 1022.
- Copyright © 1921 American Association for Cancer Research
Volume 6, Issue 4
