[Inoculability and threshold effects in transplantation of experimental tumors].

Inoculability of various experimental tumors (spontaneous, chemically-induced, solid, ascitic and leukemic) versus the amount of inoculated tumor cells (10(0)-10(7)) was studied. With small amounts of cells (10(2)-10(3)), inoculability of some tumors appeared to be nil, while in certain long-passaged neoplasms, particularly, leukemia, as few as 5-10 cells were enough. The data obtained pointed to a threshold in experimental tumor transplantation. However, quantitative analysis failed to establish one in the tumors under study. To assure transplantation, much larger study groups, e. g. of no less than 1500 animals for a breast cancer study, are required, which is hardly practicable.