Tumour response endpoints in the BA1112 rat sarcoma.

The rat rhabdomyosarcoma BA1112 has a number of features which make it a useful model for the study of tumour response to radiation therapy. It is a transplantable tumour, isologous to an inbred line of WAG/Rij rats and it elicits no demonstrable host immune response. The tumour grows locally at the implantation site and rarely metastasizes. It is known to contain hypoxic cells which reoxygenate during a prolonged course of fractionated radiation therapy. The growth and radiation response characteristics of the tumour have remained stable for over 15 years. A newly developed in vitro assay for tumour cell clonogenicity greatly facilitates the measurement of radiation dose-response curves and the monitoring of cell response following in vivo treatment. The in vivo response of the tumour to fractionated radiation therapy is analysed in terms of cellular response, reoxygenation and cell proliferation.