Thermoseed hyperthermia treatment of mammary orthotopic transplantation tumors in rats and impact on immune function.

To evaluate the effect of thermoseed inductive heating on mammary orthotopic transplantation tumors and immunologic function in rats. Walker-256 tumor cells were inoculated subcutaneously into the mammary glands of Wistar rats. Rats were allocated to five treatment groups as follows: i) C group (control group); ii) M group (magnetic field group); iii) T group (thermoseed control group); iv) H1 group (hyperthermia treatment, 45 degrees C for 30 min); v) H2 group (hyperthermia treatment, 50-55 degrees C for 10 min). Immediately, 12 and 24 h after hyperthermia, two rats were sacrificed in each group for pathological and immunohistochemical examination of the expression of PCNA and HSP70. Tumor volume was measured and long-term survival was observed. The T lymphocyte subgroup IL-2 and IFN-gamma levels were measured in C, H1 and H2 groups. Both types of hyperthermia induced necrosis and apoptosis in the tumor tissue, decreased tumor volume (P<0.05), and increased survival time (P<0.01). The expression of PCNA and HSP70 in hyperthermia group was significantly different compared to the C, M and T groups (P<0.05), Hyperthermia increased CD4+ T lymphocytes and the levels of IL-2 and IFN-gamma (P<0.05). Both types of hyperthermia can suppress the growth of mammary tumors and improve immunological function of rats.