Abstract
The effects of Corynebacterinm parvum and cortisone acetate (CA) on the primary Lewis lung carcinoma and its pulmonary metastases were investigated. C. parvum given IV either on the same day or 7 days after tumour inoculation, reduced primary tumour growth, while 2.5 mg CA (highβdose) given SC 4 and 11 days after tumour, alone or in combination with C. parvum, administered on day 0, reduced primary tumour growth to the same extent as C. parvum alone. Highβdose CA given on days 2 and 6 had no effect on primary tumour growth or the action of C. parvum, administered on day 7, while 0.05 mg CA (lowβdose) given on days 4 and 11 did not alter tumour growth or the action of C. parvum, given at the same time as tumour. Highβdose CA given 4 and 11 days after tumour caused a significant enhancement in metastases. C. parvum given to these mice on the same day as tumour significantly reduced the pulmonary nodules but only to the level found in control, salineβtreated mice. In mice given C. parvum alone, metastases were significantly reduced when compared with controls. Similarly, highβdose CA given on days 2 and 6 significantly enhanced metastases, and C. parvum on day 7 reduced their level to that found in control mice. Lowβdose CA had no effect on the number of metastases or the antimetastatic action of C. parvum. The relevance of these results to the clinical situation is discussed.