CANCER RESEARCH.

Otago Daily Times, Issue 20917, 6 January 1930, Page 14

CANCER RESEARCH.

STUDY OF SINGLE CELL UNIT. SUSCEPTIBILITY AN IMPORTANT FACTOR. - (From Our Own Correspondent.) LONDON, November 26. For the general public perhaps the most interesting part of the current report of ■ the Imperial Cancer Research Fund is the survey by Dr W. Cramer of 10, years’ .systematic investigaation into the artificial production of cancer. This wag opened up by the experiments of Fibiger in 1014, which showed that the presence of a certain parasite in the stomachs of rats frequently produced cancer, the exciting cause being presumably one of chronic irritation. Two years later it was shown in Japan that cancer could sjmilarly be produced by prolonged irritation with a non-living substance, such as tar, painted upon the ear of a rabbit. In 1921 this method of producing cancer was finally confirmed and standardised by further experiments in Copenhagen and by Drs Murray and Woglom in the Imperial Cancer Research Fund laboratory. By the continual application of tar extending over a period of many weeks cancer could be produced with reasonable constancy upon the skin of a certain proportion of mice. But various interesting facts came to light. It could never be produced under three or four months. And while a decrease in the amount of irritation applied prolonged the period before cancer appeared, an increase of the irritation did not shorten the preliminary period. A REASONABLE SUPPOSITION. Now, three months in the life of a mouse is equivalent to about seven years in the life of a man. And this was the minimum period. As a rule six months was found to be necessary to produce a mouse-tumour, corresponding to about 14 years in terms of human life. A point of immense interst thus emerged. For this was the period which had already been noted in the appearance, of human cancer, of occupational origin, amongst chimney sweeps, tar workers, and certain workers in oil industries. But not all such workers—only a comparatively few, indeed —were affected, and similarly not all raise reacted to tarpainting. Two main factors, therefore, appeared:— Susceptibility, inherent in certain individuals, and Prolonged irritation by some external agent. And it seems reasonable to suppose that these are the two necessary conditions in the production of all cancer. Moreover, jt was found that irritants of widely different character were equally effective. Intense heat and intense cold could produce cancer, after prolonged and constant application in certain subjects, as well as tar, soot, and various crude oils. It was the irritation, that is to pa y, rather than (he particular irritant, that seemed to be the significant fact. PROBLEM OF SUSCEPTIBILITY, That being the ease, as Dr Cramer remarks,'it is far more likely that freedom from cancer will be attained by studying the problem of susceptibility than hunting down the 100 and one forms of chronic irritation known and alleged to be its possible causes. “Work is already being done upon this, and it is satisfactory to know that this factor, vague as it remains, can bo studied by experiment. . It has been found that by the exhibition of certain substances the susceptibility of an organism can be increased, and this at least indicates the possibility that it can also be lessened. It is probably in the laboratory and in the study of the single coil-unit that the key to the victory over cancer will ultimately be found.