It has been shown that feeding a protein-free diet prior to injection of N-nitrosobis(2-oxopropyl)amine (BOP) can inhibit the development of pancreatic carcinoma in the hamster. The purpose of this study was to determine whether this inhibition is due to a direct effect on the pancreas or to a systemic mechanism. Pancreas transplantation was used to create four groups of two-pancreas hamsters (Group 1: protein-containing diet donor/protein-containing diet host; Group 2: protein-containing diet donor/protein-free diet host; Group 3: protein-free diet donor/protein-containing diet host; Group 4: protein-free diet donor/protein-free diet host). Animals were fed either a protein-containing diet or a protein-free diet for four weeks preoperatively. One day after transplantation, the two-pancreas animals received a 40 mg/kg body weight, subcutaneous, single dose of BOP. Animals in all groups were maintained on a regular protein-containing diet postoperatively, and were then sacrificed 42 weeks after BOP injection. The results showed that a) the incidence of carcinoma in groups 2, 3, and 4 was significantly lower than that in group 1; b) there was no significant difference in group 2 between donor and host pancreas; c) the incidence of carcinoma in the donor pancreas was lower than that in the host pancreas in groups 3 and 4. These results confirm that the protein-free diet significantly inhibits the development of BOP induced pancreatic carcinoma in the hamster. The inhibitory effect appears to act both directly on the pancreas and through an indirect systemic mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)