上顎ガン細胞核内DNA量の研究

放射線増感剤と照射によるDNA量の変動

抄録

Purpose of study:
This study was carried out to determine by microspectorophotometric method the NDA content of the nuclei of maxillary cancer cells in an attempt to investigate the relationship between the DNA content of the cancer cell nuclei and the degree of differentiation of the tumor as evaluated histomorphologically to make a comparison of the variation in the DNA content in the course of treatment by irradiation with combined use of radiosensitizer agents under different programs, to assess the value of DNA detemination as applied to the diagnosis of maxillary cancer and the evaluation of its therapeutic response. Materials and methods:
Used in the present study were 14 patients with maxillary cancer, of whom 10 had squamous cell carcinoma and 4 undifferentiated carcinoma. These patients were sinusectomized to keep the tumor in sight so that tumor tissue specimens could be collected at the most comparable possible site of the lesion both before and during the course of anticancer therapy with drugs or irradiation. Specimens thus obtained were submitted to histopathologic examination and at the. same time to the Feulgen test to determine the amount of DNA contained in cancer cell nuclei by the two wave length technique in a microspectrophotometer (Olympus MSP-A IV Model).
Results:
1) The mean DNA content (M) of the cancer cell nuclei prior to anti-cancer treatment of maxillary cancer ranged from 15.0-24.1, values for triploidy to under-pentaploidy, with a standard deviation (S) as great as 3.4-9.5. Thus, the cancer cells had apparently higher values for both M and S than noncancerous maxillary sinus or mucous epithelial cells.
2) The histogram of the DNA content of cancer cell nuclei characteristically indicated the presence of nuclei with a value for tetraploidy or higher. Nuclei having such a value accounted for 10 per cent or more of the total in almost all cases.
3) The moderately differentiated form of squamous cell carcinoma of the maxillary sinus was associated with the highest DNA content of cell nuclei as viewed in terms of M and S values. The highly differentiated type showed relatively low values for M and S. The values were low but high in other cases of cancer of poorly differentiated or undifferentiated forms.
4) The increased DNA content of cancer cell nuclei was found at 12-24 hours after administration of radiosensitizer agents (mainly 5-fluorouracil). Here the increment in the DNA content was greated with increasing dosage of 5-Fu. With irradiation implemented in combination with administration of radiosensitizers, an apparent therapeutic response was elicited as the DNA content of cancer cell nuclei diminished drastically and the tumor was reduced even macroscopically in size.
5) The results described above indicate that the DNA content of cell nuclei can provide valid evidence for diagnosis of maxillary cancer. The observed variation in the DNA content in association with administration of radiosensitizers and irradiation may also be helpful as an indicator for improved anticancer therapy, considering the mechanism of action of such agents and the irradiation schedule adopted.