CANCER RESEARCH.

Hauraki Plains Gazette, Volume XXXV, Issue 4774, 10 November 1924, Page 1

CANCER RESEARCH.

STEPS TOWARDS, KNOWLEDGE. SOME CAUSES OF THE DISEASE. i he causes, as opposed to the cause, oi cancer are gradually being elucidated (says the medical correspondent oi the London Times), 'thanks to a series of brilliant i esearches carried on within tne last two decades we are now in a position to say. that cancer can be caused in certain animals by the X-rays, by applications of paratrin and tars, and by the ingestion of parasitic worms. To some of those researches ur. Leitch and his co-workers at the Cancer Hospital have made valuable contributions, in tne current, issue of the British Medical Journal an important addition to Knowledge is described by tnem. Dr. Leitch points out Jiat in his own laboratory cancer has been produced by coal tar, tar extracts, pitch, soot, arsenic, shale oil, and industrial oils derived from shale, by crude petroleums, lubricating oil, and by a tarry substance prepared from icoprene. Obviouisly, however, the proportion of cancers arising from such agents (X-rays, tars, or worms) is small. A later research has been directed into causes if cancer operating within the body itself. The gall bladder was selected as the seat of experiment, and guinea pigs were chosen as experimental animals. They were not a very satisfactory choice —from one point of view—since the guinea pig has never bee.i known to develop any kind of carcinoma naturally. Operations weie performed and a number of small gall stones were placed in the gall bladders of a number of guinea pigsOthers of the animals had small round stones placed in their gall bladders. In a number of instances tine “glandular” type cancer developed. . it would seem to follow that, in this animal at any rate, gall atones are able to set up cancer. Nor dr they accomplish this by any special chemical in their composition, since ordinary pebbles are equally efficacious. The cause would seem to be ordinary mechanical irritation. The result is the more -nteresting that stones or “calculi” in other regions are not known to be associated with cancer, and that nobody, by animal experiment, has induced a cancer heretofore merely by mechanical irritation. A STEP FORWARD. Rasa conclusions, however, cannot and must not be drawn. While mechanical irritation does cause cancer ' in the gall bladder of the guinea Pig, there is no assurance that it will do tills in other sites or in ether animals. In all disease we have to consider the pathogenic agent tn the one hand and the susceptibel or refractory tissue on the other. Thus, if tai is applied to a mouse’is skin a skin cancer will eventually develop, but no amount of tar application will cause cancer on a rat’s or a guinea pig’s skin. Further, .tar applied to the inside of the bowel in a mouse produces no cancer—i.e., this particular tissue is not vulnerable to this particular form of irritant. This work breaks new ground, and is a clear step forward towards knowledge of the cancer problem. For the results achieved are quite new in four separate ways : (1) That is the first time a carcinoma has ever been produced in a guinea pig, and that animal has never be«n known to develop any kind of carcinoma naturally. (2) It is the first demonstration that a mechanical irritant can produce cancer. (3) It is the first time a cancer of the glandular type has ever been produced experimentally. (1) Above all, it is the first demonstration that a pathological substance developed wholly wtihin the living body (i.e., a gall stone) can produce cancer by prolonged irritation or injury.