The effect of the somatostatin analogue SMS 201-995 on experimental pancreatic carcinogenesis in the Syrian golden hamster

Abstract

Somatostatin analogues have been suggested as possible therapy for human pancreatic cancer. This paper investigates the effect of the somatostatin analogue SMS 201-995 (Sandoz) in the Syrian golden hamster model of nitrosamine-induced pancreatic carcinogenesis. Step-wise increasing doses of i.v. SMS 201-995 suppressed pancreatic juice output from a median basal value of 212 mg/kg body wt/h (Q1:Q3 = 121:334) to a median basal value of 70 mg/kg body wt/h during infusion of 5 micrograms/kg body wt/h of SMS 201-995 (Q1:Q3 = 64:102, P less than 0.05). Chronic s.c. injection of 5 and 10 micrograms/kg body wt SMS 201-995 twice daily for 3 days each week, did not affect pancreatic wet wt or pancreatic total DNA content after 1 or 6 weeks of treatment when compared to controls. The most interesting and unexpected finding in our study was that SMS 201-995 seemed to promote pancreatic carcinogenesis when administered in low dosage. More SMS 201-995 treated animals receiving 5 micrograms/kg body wt developed invasive pancreatic adenocarcinoma than controls after 15 weeks of carcinogen (4/10 animals versus 0/10, P less than 0.05, Fisher's exact test) and pancreatic involvement by tumour was more extensive (17/75 pancreatic blocks affected versus 0/71, P less than 0.001). When carcinoma in situ and microcarcinomata were analysed with invasive lesions, animals injected with 5 micrograms/kg body wt SMS 201-995 were still significantly more affected than controls (33/75 blocks versus 9/71, P less than 0.001). Hamsters injected with the higher SMS 201-995 dose (10 micrograms/kg body wt) did not show any increase in malignancy over the controls. These results suggest that the effect of SMS 201-995 on pancreatic carcinogenesis in the Syrian hamster is complex and varies with dose administered. Further work is required before its use on man can be justified.