Endocrine Abstracts

The long-acting somatostatin analogue octreotide is used either as an adjuvant or primary therapy to lower GH levels in patients with acromegaly and may also induce pituitary tumor shrinkage. However, inconclusive evidences in this respect have been produced by either single-center research paper or pooled analyses. Therefore, we performed a meta-analysis to thoroughly assess the current literature on the effect of octreotide on pituitary tumor shrinkage. A computerized Medline and Embase search was undertaken to identify potentially eligible studies. Eligibility criteria included treatment with octreotide, availability of numerical metrics on tumor shrinkage and clear definition of a clinically relevant reduction in tumor size. Primary endpoints included the proportion of patients with tumor shrinkage and mean percentage reduction in tumor volume.

The electronic search identified 2202 articles. Of these, 41 studies fulfilling the eligibility criteria were selected for data extraction and analysis. In total, 1685 patients were included in the analysis, ranging from 6 to 189 patients per trial.

Octreotide was shown to induce tumor shrinkage in 52% (95% CI: 49–54%) of treated patients. In patients treated with the LAR formulation of octreotide, this increased to 70%, (95% CI: 67–74%). In the nine studies in which tumor shrinkage was quantified, the overall weighted mean percentage reduction in tumor size was 29.3% (95% CI: 24.6–34.0%), rising to 49.5% (95% CI: 39.0–59.9%) with octreotide LAR.

Declaration of interest: I fully declare a conflict of interest. Details below:

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.