Multiphasic incidence of foreign body-induced sarcomas.

Single or multiple plastic films (unplasticized vinyl chloride vinyl acetate copolymer) of different sizes and shapes were implanted s.c. in female CBA/H and CBA/H-T6 mice. Tumor incidence increased and accelerated with increased total surface area of multiple implants or with increased size of single implants. Tumor distribution curves over time were generally multiphasic. The profiles changed in proportionate relation to implant size. These findings indicate class differences between tumors according to latency. Since latency is known to be a predetermining characteristic of foreign body-induced tumors, class differences seem to exist at the originator cell level, reflecting diversity of intrinsic carcinogenic factors.