“Not too severe, considering the danger. Whatever the lump may be, it has no business there in the breast, any more than a bullet has. If it is only a small benign tumor, the process of taking it out is very simple, and there is nothing further to do. While the patient is still under the anaesthetic, a microscopical examination of the tissue, which can be made in a few minutes in a well-equipped hospital, will determine whether the growth is malignant. If so, the whole breast is taken off, and the patient, in all probability, saved. If not, sew up the wound, and the subject is none the worse. Much the better, in fact, for the most innocent growth may develop cancer by irritation. Thirty per cent, or more, of breast cancers develop in this way.” “But irritation alone won’t cause cancer, will it?” asked Mrs. Clyde, her restlessly inquiring mind reaching back, as was typical of her mental processes, toward first causes. “No. There must be something else. What that something is, we don’t know. But we are pretty certain that it doesn’t develop unless there is irritation of some kind.” “Isn’t cancer a germ disease?” “Nobody knows. Some day we may—probably shall—find out. Meantime we have the knowledge of how to prevent it.” “How to prevent a disease you don’t know the nature of?” said Mrs. Sharpless incredulously. “That sounds like nonsense.” “Does it? What about smallpox? We haven’t any idea of what smallpox really is; but we are able to control it with practical certainty through vaccination.” “Doctors don’t vaccinate for cancer,” remarked the practical-minded old lady. “They have tried serums, but that is no use. As I said, the immediate occasion of cancer is irritation. There is overwhelming proof that an unhealing sore or irritation at any point is likely to result in the development of a cancer at that point, and at least a highly probable inference that, without such irritation, the disease would not develop.” “Then why not get rid of the irritation?”