To the Editor:— In a Letter to the Editor ( 201 :1052, 1967), Stephen C. Woodward, MD, Washington, DC, commenting upon the editorial entitled Cyanoacrylate Tissue Adhesives ( 201 :195, 1967) stated: The probability of tumor induction by a slowly absorbed cyanoacrylate tissue adhesive appeared to be nonexistent. In the study of carcinogenesis by plastic films, 1,2 it has been reported that when a plastic film is imbedded subcutaneously in animals, it becomes encapsulated by a sheath or pocket of connective tissue. It has also been shown that both the film and the pocket are necessary in the oncogenic process. Films of organic polymers as well as metal foils have been consistently tumorigenic in animals, whereas powders of the same materials, which cause no pocket formation, yield no tumors. When films of polystyrene were used, no tumors appeared if the film was removed at any period up to six months after imbedding;