Inferior outcome of neuroendocrine tumor patients negative on somatostatin receptor imaging. Issue 11 (November 2020)

• Record Type: Journal Article
• Authors: Refardt, Julie; Zandee, Wouter T; Brabander, Tessa; Feelders, Richard A; Franssen, Gaston J H; Hofland, Leo J; Christ, Emanuel; de Herder, Wouter W; Hofland, Johannes
• Is Part Of: Endocrine-related cancer. Volume 27:Issue 11(2020)
• Page Start: 615
• Page End: 624
• Publication Date: 2020-11
• Subjects: somatostatin receptor -- neuroendocrine tumor -- survival -- propensity score; Endocrine glands -- Cancer -- Periodicals; Endocrinology -- Periodicals; Cancer -- Endocrine aspects -- Periodicals; 616.9944005
• DOI: 10.1530/ERC-20-0340
• Languages: English
• ISSNs: 1351-0088

Abstract

Abstract : Sufficient expression of somatostatin receptor (SSTR) in well-differentiated neuroendocrine tumors (NETs) is crucial for treatment with somatostatin analogs (SSAs) and peptide receptor radionuclide therapy (PRRT) using radiolabeled SSAs. Impaired prognosis has been described for SSTR-negative NET patients; however, studies comparing matched SSTR-positive and -negative subjects who have not received PRRT are missing. This retrospective analysis of two prospectively maintained NET databases aimed to compare matched metastatic grade 1 or 2 SSTR-positive and –negative NET patients. SSTR-negativity was defined as having insufficient tumor uptake on diagnostic SSTR imaging. Patients that underwent PRRT were excluded. Seventy-seven SSTR-negative and 248 SSTR-positive grade 1–2 NET patients were included. Median overall survival rates were significantly lower for SSTR-negative compared to SSTR-positive NET patients (53 months vs 131 months; P < 0.001). To adjust for possible confounding by age, gender, grade and site of origin, 69 SSTR-negative NET patients were propensity score matched to 69 SSTR-positive NET patients. Group characteristics were similar, with the exception of SSTR-negative patients receiving more often chemotherapy and targeted treatment. The inferior survival outcome of SSTR-negative compared to SSTR-positive NET patients persisted with a median overall survival of 38 months vs 131 months ( P = 0.012). This relationship upheld when correcting for the main influencing factors of having a higher grade tumor or receiving surgery in a multivariate Cox regression analysis. In conclusion, we showed that propensity score-matched SSTR-negative NET patients continue to have a worse prognosis compared to SSTR-positive NET patients despite receiving more aggressive treatment. Differences in tumor biology likely underlie this survival deficit.