A study of the influence of various diagnostic and therapeutic procedures applied to a murine squamous carcinoma on its metastatic behaviour.

An experimental tumour system for the study of metastasis has been developed using a syngeneically transplanted murine squamous carcinoma of spontaneous origin. Implants of the tumour, which does not elicit a significant immune response, grew and metastasized regularly to regional lymph nodes and lungs, in a manner comparable with that of the more malignant types of human epithelioma. The system has been used to test the influece of pre-operative irradiation, regional lymph node excision, tumour biopsy and manipulation, on metastasis. Of these, only pre-operative irradiation with 2000 rad 24 h before tumour excision produced a significant differential effect--a lower incidence of metastasis. By contrast, local radiation therapy sufficient to cause complete tumour regression but insufficient to achieve long-term local cure was shown to result in accelerated metastasis. A highly significant inhibition of metastasis was observed with the drug ICRF 159, but histological features suggested that its anti-metastatic effect in this system did not depend on morphological changes which might prevent dissemination of tumour cells.