Regularities of Induction and Growth of Tumors in Mice upon Irradiation of Ehrlich Carcinoma Cells Ex Vivo and In Vivo with a Pencil Scanning Beam of Protons

The patterns of tumor induction and growth in mice under single irradiation ex vivo and in vivo of ascitic Ehrlich carcinoma (EAC) cells with a proton beam at doses of 30, 60, and 80 Gy are studied. It is shown that the frequency of tumor induction after the proton irradiation of EAC cells at a dose of 30 Gy under ex vivo irradiation was lower than after in vivo irradiation, and at doses of 60 Gy and 80 Gy, the number of tumors was the same. The temporal patterns of tumor occurrence in the ex vivo irradiation of EAC cells differed significantly from those after in vivo irradiation of the tumor: the time period during which the appearance of new tumors was recorded in the ex vivo groups was the same for all the studied doses, while when tumors were irradiated in vivo, this interval depended on the dose. The rate of tumor growth after the ex vivo and in vivo irradiation of cells does not depend on the dose, irradiation conditions, or time of their occurrence, but is significantly lower than in the control nonirradiated groups. The results obtained are of interest for understanding the mechanisms of potentially lethal damage to tumor cells, the role of the tumor microenvironment in inducing relapses, and ways to overcome them using the potential of proton therapy, as well as for developing biomedical models to find optimal targets for hadron cancer therapy.