Sequential changes in nuclear DNA content by chemotherapy observed in experimental canine gastric cancer.

It is known that the nuclear DNA contents correlate with the grade of malignancy. In this study, nuclear DNA contents of biopsy specimens taken from N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG)-induced canine gastric cancer were measured by Feulgen-DNA-cytofluorometry. The DNA content and histological findings were sequentially observed after weekly administration of 7-N-(p-hydroxyphenyl)-mitomycin C (0.8 mg/kg), a kind of mitomycin C derivative. The appearance rate of cells over 4C decreased remarkably from 18.8% to 9.86% on average (p less than 0.02) and the maximum value of distribution also went down from 9.18C to 7.33C (p less than 0.01) at the early stage of administration of the oncostatic agent when no histological change was yet observable. It might be expected that this procedure will enable the future evaluation of oncostatic effects at the cellular level more objectively.