Orchidectomy and the immune response. III. The effect of orchidectomy on tumour induction and transplantation in mice

Abstract

The effects of orchidectomy in Balb C mice on the induction and transplantation of tumours which are not obviously hormone dependent were studied. Orchidectomy prolongs the interval between subcutaneous injection of methylcholanthrene and appearance of subcutaneous sarcoma. In tumour transplantation experiments orchidectomy conferred a slight but significant protective effect when meth A tumour cells (which are syngeneic with Balb C mice) were grown in ascitic form and when the same cells grew as a solid subcutaneous tumour protection was increased. Protection was counteracted by administration of a.l.s. and partially abrogated by thymectomy combined with orchidectomy, findings that suggest alteration of cell mediated immunity as the mechanism of protection. Combination of cyclophosphamide treatment with orchidectomy increased the antitumour effect of orchidectomy alone. In contrast orchidectomy accelerates the appearance of spontaneous leukaemia in AKR mice which is known to be thymus dependent. The explanation is probably that orchidectomy, by causing thymic hypertrophy increases the number of cells at risk of malignant transformation. It is suggested that some of the beneficial effects of the endocrine treatments of cancer may result from alteration of host immunity and have therefore, a range of application wider than in the management of endocrine dependent tumours alone.