Risk assessment of carcinogenesis at implantation sites

Of the 98 foreign-body or scar-related cancers reported in the literature, over 25 percent have developed within 15 years, and over 50 percent within 25 years. Substantial numbers of various implants have now been in place for 10 to 20 years. Since at least 25 percent of cancer cases should already have occurred, the low number actually observed permits the prediction that the incidence of cancers at implantation sites will remain low. This conclusion is supported by studies on 27 specimens of chronic foreign-body reactions against a variety of implants that had been in situ for 1 to 19 years. Employing a cell-culture technique previously developed for experimental mice, an attempt was made to identify specific precancer cells in the tissues. None were detected, in contrast to foreign-body reactions of mice, in which the incidence of foreign-body tumors is high.