Synchronization of human tissues and its consequences for cancer therapy in ENT. Cell kinetic and clinical studies

Intravenous chemotherapy with syndronization in advanced cancer of oral cavity and oropharynx

Sixty-one patients with locally advanced squamous cell carcinomas of oral cavity and oropharynx were treated with chemotherapy, intravenously applied, in addition to radiation and/or surgery. An attempt was made to synchronize the tumor cell population by application of low doses of Vinblastine and the subsequent chemotherapy was based on the uptake of 99m-Tc --labelled Bleomycin in the tumor as an indication of synchronization. Increased number of mitoses in aspiration biopsy specimens and shift in the DNA distribution pattern on DNA histograms were taken as indicative of synchronization. A 50--100% regression of the tumor was achieved in 19 out of 38 patients with residual or recurrent tumors. The results were better in those patients, who received chemotherapy based on individual Tc-Bleomycin uptake curves. In 23 patients with previously untreated T3 tumors of oral cavity and oropharynx the results were somewhat better, but there was not statistically significant improvement on attempts with synchronization in this small series. There were no serious complications connected with chemotherapy.

[Critical reflections to the problem of timing in the synchronization therapy of human malignant tumors. Mitotic-index determination, cytophotometric and radioautographic studies (author's transl)]

Formerly (1969) we have been able to demonstrate that during a lengthy inhibition of the DNA synthesis with 5-fluoro-uracil (FU), cells assemble just before, at the outset of, and within the S-phase. By taking off the inhibition, these cells start off together for the rest of the life cycle and pass the S, G2 and M phase like a wave. By the experimental condition given, the time required for passing the S phase was rather constant for all tissues. It generally took about 8 h. The sensitivity of cells to radiation depends on the current phase of their life cycle. Normally they are highly radiosensitive during the transition from G1 to S phase and within the G2 phase. Therefore we tried to improve the effectiveness of radiotherapy by radiating the synchronized cell population in the G2 phase. In clinical treatment we give an infusion with 1 g FU in 1000 ml 5.4% Glucose for 12 h. 8--9 h after the end of the infusion radiation will be applied (Betatron, individual doses: 500 rad). This treatment will be repeated until a total dose of 5000--6000 rad. Until now nearly 300 cases of patients treated in this way have been published. The 5 year-results show only in about 60% of the patients a fast reduction of the tumor. The long term results are unsatisfactory. Beside many other points the most important reason for these clinical results might be the individual length of the S phase of the tumors which prevents that radiation can be given exactly in G2 phase in each case. With mitotic-index determination, with cytophotometric investigations and the double labelling technique (3H- and 14C-Thymidine) we therefore tried to find an answer to the following questions: 1. How long is the DNA synthesis time in the individual case of human ENT tumors? 2. Does the application of FU influence the length of the S phase? 3. Will the synchronization-degree become higher by using other methods of cell cycle inhibition? With the above mentioned experimental methods we found that the length of the S phase in human tumor spreads from about 8--16 h in the individual case. The application of FU has no influence on DNA synthesis time. By using FU the degree of synchronization is about 2.5 in according to former experimental work and that of other authors. These results will be discussed in detail as well as the conclusion we draw from our experiments: to give radiation not in G2 but in G1/S of the cell cycle. Long-term observation of the patients and further animal experiments shall demonstrate whether this technique of synchronization therapy will improve the clinical results.

Cell kinetics and programmed chemotherapy for gynecologic cancer. I. Squamous-cell carcinoma

The results of current investigation into cellular kinetics of both normal and abnormal human genital tissue have stimulated interest in programming chemotherapeutic drug regimens for the treatment of genital cancer. This report outlines the results of cell kinetic studies of normal and abnormal squamous epithelium of the female genital tract and presents preliminary results of a regimen utilizing methotrexate, hydroxyurea, and vincristine in patients with far-advanced squamous-cell cancer of the vulva, vagina, and cervix. A total of 92 patients have received 444 courses of programmed chemotherapy by either pelvic intra-arterial infusion or systemic administration of the drugs. Our results are presented and the theoretical basis of the research is discussed.