Medicine: If Men Were Mice

Cancer is not inherited but susceptibility to it is. This theory, today almost universally accepted as fact, was announced to a mightily impressed medical world in 1912. Last week the woman who announced it, now grey-haired and granite-faced, left Chicago for her first vacation in 26 years.

Indefatigable Professor Maud Slye, pathologist of the University of Chicago, will use her “vacation” to address the International Congress for the Control of Cancer which meets in Brussels next month. Also at Amsterdam, Berlin, Paris, London, perhaps Copenhagen, she will give the case histories of 5.000 cancerous and noncancerous mice, renew her old plea that complete medical records be kept for human cancer as she has kept them for her army of rodents.

Miss Slye has autopsied 138,700 mice.

She can walk through her Midway laboratory (she lives across the street from it), glance at the case histories of 9,000 mice, tell what kind of cancer, if any, each will develop. She can tell 98 times out of a hundred how soon the disease will appear and in what part of the body.

Firmly established is the Slye doctrine that susceptibility to cancer is inherited as a recessive Mendelian character, transmitted by a single gene. Resistance to the disease is a dominant character, and represses, but does not obliterate, the susceptibility factor whenever they occur together. A resistant individual mated to a susceptible one will have resistant offspring. But these offspring carry the susceptibility gene concealed in their germ plasm, and if they mate with susceptibles the second generation will be liable to cancer. The Slye mice show that not only inherited susceptibility but also some injury or chronic irritation is necessary for the malignant growths to appear. Dr. Slye has mice prone to cancer of the jaw which never develops because she keeps their incisors filed short, preventing tooth irritation.

Said Professor Slye last week before leaving: “If we had records for humans comparable to those for my mice, we could stamp out cancer in a generation. Sweden has made a start toward such records, but no other country in the world is making such an effort. Meanwhile, cancer is a leading cause of death, and as we make progress in heart diseases, it is likely to become the first cause in a comparatively short time.”