Using percutaneous computed tomography-guided core needle biopsy of liver metastases from gastroenteropancreatic neuroendocrine tumors to identify inter-tumor grading classification heterogeneity

Abstract Background We used percutaneous computed tomography-guided core needle biopsy (PCT-CNB) of liver metastases from (gastroenteropancreatic neuroendocrine tumors) GEP NETs to identify inter-tumor grading classification heterogeneity. Methods We retrospectively investigated 92 patients with liver metastases in GEP NETs using PCT-CNB; 76 patients had tissue from liver and primary sites while 16 had tissue from liver and secondary liver sites. For tissue sampling, Ki-67 immunohistochemistry was performed and grading classifications was determined. Inter-tumor grading classification heterogeneity and associated changes on patient survival were also evaluated. Results No procedure-related mortality was recorded during and after biopsy. In 37/92 patients (40.2%), grading classifications changed: 13 patients increased from G1 to G2, 2 increased from G1 to G3, 5 decreased from G2 to G1, 14 increased from G2 to G3, 1 decreased from G3 to G1, and 2 decreased from G3 to G2. Patients with NET G1 or NET G2 grades had better progression-free survival (PFS) and overall survival (OS) when compared with NET G3 grade patients (P=0.001 and P < 0.001, respectively). OS rates at 5 and 10 years were 67.5% and 26.0% for stable G2 patients, but decreased to 46.4% and 23.2% for increased G2 patients (P=0.016). Conclusion The PCT-CNB of liver metastases from GEP NETs showed grade differences between the liver tumor and primary site/secondary liver metastases. Also, when G2 increased, OS significantly decreased.