Efficacy of boron neutron capture therapy on liver metastases of colon adenocarcinoma: optical and ultrastructural study in the rat

The effect of neutron boron capture therapy (BNCT) was studied in rat tumor liver cells after induction of the liver metastases by splenic inoculation of cells from DHA/K12/TRb line. Ten days following the treatment, the BPA was injected into rats and therefore the animals were sacrificed, the liver was exposed to neutron irradiation and processed. In some experiments the liver was reimplanted (after irradiation) in syngenic animals and studied 3 days later, following sacrifice. Samples of tissue obtained from metastasised and non-metastasised areas of the liver parenchyma, before and after the neutron irradiation, were examined in light microscopy and electron microscopy. The analysis pointed out damages induced by the neutron treatment in single tumor cells mostly localised in the synusoidal blood stream. Debris and apoptotic cells were sometimes observed in the neoplastic nodules before treatment, while the tumor cell death (apoptosis) increased in the tumor cells following BNCT treatment. An intense scavenger activity of Kupffer cells after irradiation was accompanied by a strong acid phosphatase reaction detectable in wide cytoplasmic areas. In the liver parenchyma of reimplanted animals, the presence of large collagen bundles spread among the hepatocytes was observed at electron microscopy.