Clinical validation and diagnostic accuracy of 99m Tc-EDDA/HYNIC-TOC compared to 111 In-DTPA-octreotide in patients with neuroendocrine tumours: the LACOG 0214 study.

^99m Tc-EDDA/HYNIC-TOC is an easily available and cheaper radionuclide that could be used for somatostatin-receptor-based imaging of neuroendocrine tumours (NETs). We aimed to evaluate the diagnostic performance of ^99m Tc-EDDA/HYNIC-TOC compared to ¹¹¹ In-DTPA-octreotide in patients (pts) with NETs. We performed a prospective diagnostic study including pts with biopsy-confirmed NET and at least one visible lesion at conventional imaging. Two independent nuclear medicine physicians evaluated pts who underwent ^99m Tc and ¹¹¹ In scans and images. The primary outcome was comparative diagnostic accuracy of ^99m Tc and ¹¹¹ In. Secondary outcomes include safety. Nine pts were included and performed 14 paired scans. Overall, 126 lesions were identified. ^99m Tc demonstrated superior sensitivity both when all images were analysed (93.7, 95% CI 88.1% - 96.8% versus 74.8%, 95% CI 66.6 - 81.6%, p < 0.001) and when liver-specific images were analysed (97.8%, 95% CI 92.7% - 99.5% versus 85.1%, 95% CI 76.6% - 91.0%, p < 0.001). ^99m Tc was also associated with a lower negative likelihood ratio (LR) (0.002, 95% CI 0.009 - 0.1 versus 0.19, 95% CI 0.12 - 0.42, p = 0.009) when evaluating hepatic lesions. Adverse events happened in 3 pts after ¹¹¹ In and in 2 pts after ^99m Tc, all grade 1. The ^99m Tc demonstrated a higher sensitivity overall and a better negative LR in liver-specific images compared to ¹¹¹ In in pts with NETs. Our findings suggest that ^99m Tc is an alternative to ¹¹¹ In and is especially useful in ruling out liver metastases. NCT02691078.
Competing Interests: Dr Moriguchi-Jeckel and Dr Werutsky report grants from Financiadora de Estudos e Projetos (FINEP) for the conduct of the study. Drs R. Madke, Viana, Nabinger, and Fernandes report employment relationships with the RPH Group. Dr. Werutsky reports personal fees from AstraZeneca, Bayer, Beigene, Daiichi Sankyo, Genentech/Roche, GSK, Lilly, MSD, Novartis, Pfizer, Sanofi, and Seattle Genetics outside the submitted work. The other authors declare that they have no conflict of interest.
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