The Virus Tumors and the Tumor Problem

Abstract

Not long ago, in the dark ages of medicine, one could think nearly anything about disease because one knew almost nothing. Theoretical system succeeded system, from humours to homeopathy. Opinions strongly held appeared like realities and were acted upon as such. Now for most diseases all this is at an end: fact has killed fancy. Not as concerns tumors, though. Knowledge of these is still so fragmentary that the mind can play at will, devising explanations as in the bad old days: the tumor problem is the last stronghold of metaphysics in medicine. But it is a stronghold closely besieged. Each new physical, chemical, or biological discovery is brought to bear upon it; and whereas formerly the doctor asked himself what this or that idea might mean for the tumor problem, now he is increasingly enabled to ask what this or that fact means. I will treat here of facts which show certain tumors to be due to viruses and will deal with the implications of this knowledge. Let us glance first at the general progress toward an understanding of the neoplasms. Since the turn of the century men have recognized that animal tumors provide an abundant material for studies of the general problem, and have succeeded by transplantation in perpetuating many of them for experimental purposes. Already familiar with the immense world of tumor morphology, they have worked out the laws regulating tumor growth; they know something of the chemistry of the neoplastic cell, and a good deal about hereditary factors in the incidence of cancer. Taking pattern from nature, they have learned how to induce tumor formation at will, through the action of various agents on the tissues; they have purified or synthesized some carcinogenic substances; and by investigations of their structure have taken a first step toward understanding how they act.