Biomedical subjects

J G Schaffner

Publications and source records attributed to J G Schaffner.

3 recordsLinked to original sources

PubMed1977

Solid tumor models for assessment of different treatment modalities: therapeutic strategy for sequential chemotherapy with radiotherapy.

A therapeutic strategy for combined radiotherapy and chemotherapy of experimental solid tumors has been devised. More effective utilization of combined chemotherapy and radiotherapy may be realized clinically if comparable information is obtained in man. The overall treatment efficiency of successive courses of treatment has been determined by a method that defines tumor response quantitatively over an entire spectrum of tumor responses. The findings of this study have shown that an individual tumor that responds well to the first course of therapy will respond well to the second and third courses of combined modality therapy. Various solid tumors in different animal species have demonstrated variability of response to treatment, analogous to the many types of response found clinically.

Animals↗

PubMed1976

Solid tumour models for the assessment of different treatment modalities: IV. the combined effects of radiation and 5-fluorouracil.

Neither radiation alone (375 to 1500 rad) nor5-fluorouracil (FU) alone (50-250 mg/kg) is sufficient to prevent an increase in the volume of the solid tumour model hepatoma 3924A. However, as little as 750 rad with 100 mg/kg FU can reduce the tumour below the volume at the time of treatment for as long as 14 days. A series of combined FU and radiation doses given every 11 days should then result in successively smaller tumour volumes until the tumour is eradicated. Changes in tumour volume were analysed by two different methods: (1) tumours in each treatment mode were grouped together and the average response to treatment determined, and (2) tumour volume changes in individual tumours were analyzed utilizing the chi2 technique, which fits the logarithmic tumour volume change with time to polynomials. This two-directional method of analysis has the advantage of permitting both an overview of the main effects of treatment via the averages, and at the same time a detailed examination of the mechanism by which these effects occur through the analysis of individual response. The results suggest that, in addition to concentrating on the cellular response immediately after therapy, greater emphasis should be placed on the kinetic changes of the tumour 1-3 weeks after single or multiple modality therapy. These findings demonstrate how the sequencing of single and/or combined treatment modalities may be investigated in order to detemine how best to obtain maximum effects of treatment on different types of tumours following recovery of the host from the previous treatment series.

Animals↗

PubMed1976

Solid tumor models for the assessment of different treatment modalities: systematics of response to radiotherapy and chemotherapy.

The change of tumor volumes (efficiency) with local tumor radiation doses from 375R to 3750R and 5-fluorouracil (5-FUra) from 50 to 250 mg/kg was assessed in rats bearing hepatoma 3924A. The data were analyzed utilizing a chi2 technique which fits the logarithmic volume response to polynomials. This provided greater flexibility in selecting different mathematical forms, and allows more accurate description of tumor changes after treatment than the least squares analysis previously used. Quantitative information can be obtained on one tumor following treatment by this method. This information is more analogous to the management of a patient with a solid tumor. The results show a continuous increase in efficiency of radiation throughout the radiation dose range from 375R to 3750R. The efficiency of 5-FUra increased slightly but did not continue to increase with doses of 5-FUra higher than 150 mg/kg. This suggests that factors such as toxicity to the host may prevent further increases of the effectiveness of 5-FUra. The time of minimum tumor volume change after radiation was approximately 6 days and for 5-FUra, 6 days. The time for maximum tumor volume change for 5-FUra was 12 days. There was a slight trend upward for maximum growth for increasing radiation doses from 18 to 22 days. The time of occurrence of both minimum and maximum tumor volume change after treatment showed little relationship to increasing doses of radiation and 5-FUra. Parallel studies have shown that the maximum rate of tumor volume change occurs shortly after the recovery of the host from the effect of 5-FUra. It is feasible, therefore, to use chemotherapy alone or in combination with radiotherapy, and optimize the scheduling of these treatment modalities with recovery of the host from previous therapy.

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