Effect of film size on production of foreign body sarcoma by perforated film implants.

Sarcoma may arise on unabsorbable foreign bodies in rodents and more rarely in man. Perforations of the implant reduce its carcinogenicity so that nitrocellulose filters of pore size 0.45 micron have failed to induce tumour. We examined whether increase of surface area would restore carcinogenesis to film with such pore size. Nitrocellulose filters of 25 mm diameter and pore size 0.45 micron were implanted singly, in pairs and in trios subcutaneously in 3 respective groups of BALB/c mice (total 97) and observed for sarcomagenesis for 100 weeks. No tumour arose on the singles (surface area 0.98 mm2), while 7 arose on the paired (1.96 mm2) at a mean of 54 weeks and 16 on the trios (2.95 mm2) at a mean of 46 weeks (differences significant at p > 0.01). A sufficiency of surface area restores carcinogenicity to perforated foreign surfaces in mice. Surface area is dominant over film perforation size in film sarcomagenesis.