Journal of Theoretical Medicine
Volume 2 (2000), Issue 4, Pages 297-305

Repopulation of Tumour Cells during Radiotherapy Is Doubled during Treatment Gaps

1Centre of Oncology Maria Sklodowska-Curie Memorial Institute Branch in Gliwice Wyb, Armii Krajowej 15, 44-101 Gliwice, Poland
2Department of Automatic Control, Silesian Technical University ul. Akademicka 16, 44-100 Gliwice, Poland

Received 24 November 1998; Accepted 9 August 1999

Copyright © 2000 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this work is to analyse the proliferation of tumour cells in the treatment gapduring the radiotherapy for head neck cancer.

Material and Methods: The clinical material is based on records of head and neck patients treated by radiotherapyalone in our institution. The effect of radiotherapy was assumed to be described by a linearquadratic model. The patient data were fitted directly to the radiobiological model and theparameters were estimated using maximum-likelihood procedures.

Results: According to our model results of treatment were significantly correlated with Normalised Total Dose of radiation, the tumour progression (according to TNM), the overall treatment time and the gap duration. The laryngeal cancers had better prognosis then cancers of oroand nasopharynx. When the treatment time is prolonged without treatment interruptions 0.36 Gylday is lost due to the repopulation of tumour cells. During the treatment gap proliferation is faster and 0.67 Gylday is lost.

Conclusion: Proliferation of tumour cells is faster during the treatment gap then during the days with irradiation.