the article discusses public efforts to control cancer in brazil from the 1920s to the close of the 1940s. it examines the process which brought about creation of the inspectorship to combat leprosy, venereal diseases, and cancer within the national department of public health. creation of the inspectorship was the first public action to target cancer and, while it was not far-reaching, its emergence enables us to understand the professional field of cancer at that time. the text also points to the role played by the diffusion of electrosurgery in expanding medical interest about cancer and in the founding of the cancerology center in the federal district. it discusses the establishment and first decade of activities of the national cancer service, endeavoring to link the service's initial profile with the issues that guided its history.