RECENT ADVANCES IN CANCER RESEARCH*

Abstract

EXPERIMENTAL cancer research is less than fifty years old, even younger than bacteriology ; a few of those who began it are still active. It started when the rewards of the close observational study of human cancer had become small. Then for the first time medical scientists paid attention to the fact that animals have tumours too-a fact known for some while. With the demonstration that these growths are true neoplasms (new growths) and the transfer of some of them from host to host, things got under way. At first hopes ran high that the cause of cancer would soon be found ; but then it became clear that the animal tumours maintained by transplantation carried the secret along with them. Nothing could be procured from the tumour cells which would cause other growths, and anything killing them, in even the most subtle way, brought the neoplastic process to an end. Furthermore, the transplanted tumours called forth no resistance of practical significance. The cultivation of cancer cells in vitro, though occupying many workers, contributed no deep-going enlightenment, and until 1915, when tumours were purposely induced by means of tar, workers were unable to get at the conditions determining the occurrence of neoplasms. Until then observations on the 'precancerous states' of man had been the sole reliance of the investigator, since the spontaneous growths of animals had progressed too far when first encountered to be informing. Now at last the conditions leading to cancer could be got at experimentally.