Systematic literature review of the antitumor effect of octreotide in neuroendocrine tumors

AIM To provide a comprehensive examination of the existing evidence of the antitumor effect of long-acting octreotide in neuroendocrine tumors(NETs).METHODS A systematic literature review of clinical trials and observational studies was conducted in PubM ed, EMBASE, and Cochrane through January 18, 2017. Conference abstracts for 2015 and 2016 from 5 scientific meetings were also searched.RESULTS Of 41 articles/abstracts identified, 13 unique studies compared octreotide with active or no treatment. Two of the 13 studies were clinical trials; the remaining were observational studies. The phase 3 Placebo-Controlled, Double-Blind, Prospective, Randomized Study of the Effect of Octreotide long-acting repeatable(LAR) in the Control of Tumor Growth in Patients with MetastaticNeuroendocrine Midgut Tumors clinical trial showed that long-acting octreotide significantly prolonged time to tumor progression compared with placebo in patients with functionally active and inactive metastatic midgut NETs; no statistically significant difference in overall survival(OS) was observed, possibly due to the crossover of placebo patients to octreotide. Retrospective observational studies found that long-acting octreotide use was associated with significantly longer OS than no octreotide use for patients with distant metastases although not for those with local/regional disease. CONCLUSION The clinical trial and observational studies with informative evidence support long-acting octreotide's antitumor effect on time to tumor progression and OS. This review showed the rarity of existing studies assessing octreotide's antitumor effect and recommends that future research is warranted.