This study was performed to grasping the sensitivities of radiation and a chemotherapeutic agent, Pepleomycin (PEP), on oral squamous cell carcinoma objectively by examining the relationship between clinical effects (tumor regression rates) and time-lapse changes in the nuclear DNA content and nuclear area of cancer cells during treatment.
A total of 26 cases of oral squamous cell carcinoma were studied. The nuclear DNA content and nuclear area were simultaneously measured by Vickers M 86 scanning microdensitometer after Feulgen staining.
The results were as follows:
1. With referring the nuclear DNA content of lymphocytes as control to be 2.0 C, the average values for each of the cases came within the range of 2.4-5.4 C before treatment. The frequency of the cells over 4.0 C was 7-74%. The average nuclear area was 46-120 p2. There was positive correlation between the nuclear DNA content and nuclear area. But the correlation ratio varied depending on cases.
2. In cases which showed remarkable effects (4 cases) and moderate effects (7 cases), the variances of the nuclear DNA content and nuclear area and the frequency of cells in those which showed twice the modal C value, i. e. the cells at the G
2M phases, increased in early stages of treatment. Furthermore, these cases presented polyploidization in the DNA histogram and diffusion in the scattergram. In cases which showed slight effects, these changes tended to delay (6 cases). In cases which exhibited no effects, changes were poor or almost unobserved. These changes almost invariably preceded the appearance of clinical effects.
3. In cases where modal C value was 4.0 C region or obscure, which were categorized as mode III type, which showed the poly-peak type in the histogram, and which showed high correlation between the nuclear DNA content and nuclear area (the IV type in the scattergram) before treatment, a little change was noted in the DNA histogram after treatment. Many of these cases exhibited no effects clinically. Furthermore, it was found that cells characterized by hyper 2.0 C and small nuclear area were predominant among the remaining cancer cells.
From these findings, it is conceivable that the changes in the nuclear DNA content and nuclear area in the course of treatment are related to the G
2 block effect of radiation and PEP, reflecting some aspect of cell kinetics. Therefore, these analysis seem to have an important significance in the objective evaluation of therapeutic effects.
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