Rapid induction of sarcomas in rats by combination of nickel sulfide and 3,4-benzpyrene.

The interval between administration of carcinogen and development of sarcomas was significantly shorter in male Fischer rats that received bilateral injections into thigh muscles of a combination of 10 mg of Ni3S2 and 5 mg of 3,4-benzpyrene (Group C) than in rats that received only 10 mg of Ni3S2 (Group A) or only 5 mg of 3,4-benzpyrene (Group B). No sarcomas developed in control rats (Group D), which received only the injection vehicle (pencillin suspension). The period between injection of carcinogens and initial palpation of tumors at the injection sites averaged 18 ± 3 weeks in Group C versus 26 ±5 weeks in Group A and 31 ± 10 weeks in Group B (p < 0.001). The period between injection of carcinogens and death from sarcoma averaged 24 ± 5 weeks in Group C versus 33 ±5 weeks in Group A and 41 ± 11 weeks in Group B (p < 0.001). The proportion of primary sarcomas which were classified as rhabdomyosarcomas was 91% in Group C versus 81% in Group A and 13% in group B. This study furnishes (a) additional support for speculations concerning carcinogenic interaction between nickel compounds and polycyclic aromatic hydrocarbons and (b) a rapid and convenient experimental technique for inducing rhabdomyosarcomas in rats. This technique is well adapted for use as a laboratory exercise in neoplasia for pathology students.