Cancer Permeation: Processes, Problems, and Prospects—A Review

Permeation is the scientific term introduced in 1905 by Handley to signify the spread of cancer cells in continuous columns within the lymph vessels. The phenomenon itself was known to workers of much earlier times and, to date, its processes largely have been documented. However, some problems have arisen. There is, for example, considerable confusion because different authorities have classified it under both direct and metastatic spread. Evidence is therefore adduced from the literature to show that the columns of cancer cells seen in permeation are not absolutely continuous but partially continuous. It is this element of discontinuity that confers on permeation the status of a metastatic phenomenon. If this status is recognized, a continuing source of confusion will disappear from the literature and new prospects will open in this important facet of oncology.