Effect of Nocardia rubra cell-wall skeleton on cancer prevention in humans.

The retired workers at the chemical weapons plant in Japan are regarded as a high-risk group for cancers. Under the Cancer Preventive Program, Nocardia rubra cell-wall skeleton (N-CWS) was administered to 80 workers directly involved in the production of sulfur mustard and 66 workers engaged in work related to sulfur mustard production. Untreated workers whose age, sex, duties and duration of work at this factory were individually matched to the N-CWS-treated workers were used as controls. During a 4.5-year observation period, development of cancers was found in 7 treated workers and 17 untreated controls. After elimination of the influence of the difference in smoking level, the incidence of subjects who developed cancers was compared statistically between the N-CWS-treated workers and the untreated controls and a significant suppression of development of cancers was noted in the N-CWS-treated workers. Thus, it was concluded that the administration of N-CWS could prevent cancer development in humans.