The so-called pre-can-cerous stage of malignant disease may be due to disturbances of nutrition, to previous injury, to congenital defect, or to other departures from the normal conditions. Senility and decadence of tissues which have passed the period of their usefulness and are about to undergo physiological rest are predisposing factors. Predisposing conditions also exist in certain parts of the body where embryo-logical vestiges or rests are found, and in certain regions, as the pylorus and the caecum, and at the lines of junction of skin and mucous membrane. In certain situations precancerous conditions can be readily recognised; this especially applies to the tongue, lips, larynx, uterus, and the skin, suggesting strongly that cancer is a new implantation on a prepared ground ; probably, if we could only find it, every cancer, whether external or internal, follows on a pre-cancerous condition, such as cancer of the gall-bladder on ulceration produced by gall-stones, cancer of the stomach on chronic gastric ulcer, epithelioma of the penis on irritation under a phimosis, cancer of the bladder on papilloma or on ulcers due to calculi, and cancer of the rectum and colon on stercoral or other ulcers. The liability of benign tumours, especially on epithelial surfaces, to undergo malignant changes is well recognised, hence the removal of such is generally advisable.

A general acceptance of the view that cancer has usually a pre-cancerous stage, and that this stage is one in which operation ought to be performed, would be the means of saving many useful lives, for it would lead to the removal of all suspicious epithelial conditions before the onset of cancer.

I hold that the arrest or removal of known causes as well as the abolition of discoverable pre-cancerous conditions, whenever or however occurring, constitute true preventive treatment.

Pre-cancerous conditions of the stomach are in certain cases distinctly recognisable, and if diagnosed and treated might save many patients from carcinoma. As the stomach is one of the commonest sites of cancer, if even a percentage of cases can be saved from malignant disease by timely treatment a great advantage will have been gained.