Original Article Metastases Development Following Local Tumour Treatment

Abstract. Transplantable mouse methylcholanthre-ne-induced fibrosarcoma (CMC4 tumour growing in CBA/HZgr mice), characterized by lung metastases developing shortly after local tumour cell transplan-tation, was used as an experimental model to investi-gate the problem of tumour metastases after local tumour treatment. Surgery and/or irradiation were performed on locally growing tumour of particular size. Further, heavily irradiated, viable but not di-viding tumour cells, imitating the situation in treated tumour-bearing organism, were injected intraperito-neally in a parallel group of treated tumour-bearing mice. The animals were killed 35 days after tumour transplantation and the number and volume of lung metastases were determined. Depending on the treat-ment performed, when the tumour mass was reduced or even eliminated, the number of lung metastases and their volume were significantly lower than in control mice, but the addition of tumour mass (injec-tion of heavily irradiated tumour cells) resulted in a significant increase in lung metastases parameters, pointing to a possible role of the host’s immune reac-tion against the tumour. Further, the release of a sim-ple molecule, such as nitric oxide, from tumour mass seems to be detrimental for the survival of tumour cells and subsequently their metastases through the induction of angiogenesis and possible suppression of immune reaction. Thus, complex mechanisms could be involved when a locally growing tumour is exposed to a particular therapeutic approach