Biological properties and response to X-rays of a multiple generation C3H carcinoma

Abdelaal, Abdelaal Selim (1979) Biological properties and response to X-rays of a multiple generation C3H carcinoma. PhD thesis, University of Glasgow.

Abstract

A multiple generation C3H mammary adenocarcinoma was serially transplanted at intervals of 2-3 weeks over several years, using a tumour cell suspension. The growth pattern may be described by a Gompertzian pattern, with the doubling time increasing from 0.5 days at 2 mm mean diameter to about 3 days at 10 mm mean diameter. Histologically, the tumour appeared poorly differentiated with areas of necrosis; an appearance suggestive of extensive hypoxia. The very high TCD50 of 67 Gy was compatible with this suggestion. A characteristic pattern and rate of tumour regression existed after irradiation with X-rays alone and in combination with the hypoxic cell radiosensitizer "Misonidazole". The rate of regression seemed to reflect only the rate of removal of the doomed tumour cells, cell debris and the efficiency of the mechanisms responsible for clearance after irradiation. The similar pattern of regression that emerged following non- curative and curative doses of radiation strongly suggested that the rate of regression is a poor indicator of radiation curability. However, in completely regressed tumours, a high probability of local control was observed, once an incidence of complete regression of more than 60 per cent was attained. In the present work, there was a definite growth restraint of recurrent tumours as a result of radiation damage to the txamour bed rather than an intrinsic cellular alteration in the surviving tumour cells. Clearly, this tumour bed effect should be considered in the analysis of the growth delay of these tumours. The magnitude of this effect, however, was difficult to assess from the growth studies of recurrent tumours. Furthermore, growth studies of transplanted tumours at the sites of previously cured tumours and at pre-irradiated sites offered only limited help in this assessment. The results obtained at these sites, with their discrepancies, pointed to the need for further studies before a possible extrapolation to the situation of recurrent tumotars. The recovery capacity from sublethal damage (SLD) was found to be similar to other tumovir systems. However, the values obtained using the cure data differed from those using the delay in growth data. The latter also showed the Elkind pattern (peaks and troughs) characteristic of the split dose experiments. These observations indicate the caution needed in the interpretation of the results using either set of data. This is especially true when comparing the recovery from SLD of various tiomours. Although Misonidazole was used mainly to understand the gross response of the tumours following irradiation, its potency in radiosensitization of the hypoxic tumour cells was also confirmed in the present work. The immunological studies of the tumour system have drawn attention to the possibility of an immune-suppression rather than an immuno-stimulation status of tumour bearing mice. There appeared also to be a possibility of growth enhancement when attempting immunization of the animals. Finally, comparative analysis of the biological characteristics of the present tumour and its first generation counterpart, clearly showed that serial transplantation led to several morphological and biological changes.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: A HW Nias
• Keywords: Oncology
• Date of Award: 1979
• Depositing User: Enlighten Team
• Unique ID: glathesis:1979-72403
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 24 May 2019 15:12
• Last Modified: 24 May 2019 15:12
• URI: https://theses.gla.ac.uk/id/eprint/72403