[Cancer of the respiratory tract observed in workers having retired from a poison gas factory].

Okunojima, a small island in the Inland Sea of Japan, off the shore of Takehara city was notorious for the production of poison gases from 1927 to 1945. Of the gases produced there, yperite and lewisite were the most poisonous and caused severe residual damage. It has been ascertained by studies conducted to date that the retired workers of this poison gas factory have a high risk of various types of malignant tumors including cancers of the respiratory tract. Such cancers observed in the retired workers from the poison gas factory are characterized by the following clinical features. Cancers are mainly central-type tumors with the site of development distributed from the airway to the hilar region and histologically, squamous and undifferentiated cell carcinoma predominate. Recently, the occurrence of malignant tumors has been discussed in relation to suppressed immune competence. Such disturbance of the immunological surveillance system seems to induce malignant changes of normal cells. On the other hand, we have demonstrated that the retired workers often showed impaired immunity. Therefore we considered that potentiation of immunity might possibly prevent the occurrence of malignant tumors and we took steps to enhance the immune competence of the retired workers with N-CWS. Its effect in preventing carcinogenesis will be shown in the near future.