Experimental studies into the effect of nitrous oxide on tumour cell growth.

The effect of nitrous oxide on the growth of two types of ascites tumour in mice was investigated. The mice in the first two trials were injected with tumour cells, divided into three groups and exposed to one of the following atmospheres: (1) air; (2) 25% nitrous oxide; (3) 40% nitrous oxide. After treatment, the volume of ascites fluid and the concentration of cells were measured. It was found that nitrous oxide treatment significantly lowered the number of cells grown in the case of Ehriich ascites tumour but had no effect on the growth of 2146 tumour. Two further studies were made in which treatment with nitrous oxide preceded injection of tumour cells; these failed to reveal any effect on tumour growth. Possible applications of nitrous oxide in the treatment of cancer are discussed.