Growth rate, morphology and drug responses of rat lung tumours growing at different sites.

Three rat squamous cell carcinomas and an adenocarcinoma were grown in the spleen to investigate whether the spleen is a suitable site for tumours to be grown without cyst formation for treatments such as interstitial brachytherapy. Morphological features and growth rate were compared with those of tumours growing subcutaneously and intrapulmonarily. Tumours were also subjected to cytostatic drugs. Spleen tumours grew without cyst formation. Volume doubling times of spleen tumours were shorter than those of flank tumours, while flank tumours grew faster than lung tumours. Specific growth delays of spleen tumours were not different from those of flank tumours and those of lung tumours were smaller or not significantly different from those of flank tumours.