Table 7.

Eligibility criteria for biopsy of primary and liver metastases.

Study characteristic	Inclusion criteria	Exclusion criteria
Patient population	Patients with primary neuroendocrine tumors and/or NET liver metastases	Children or adolescents (under the age of 18 years old)
	Patients who underwent a biopsy of the primary and liver metastasis
	Patients who underwent multiple biopsies of the liver metastases and/or healthy parenchyma
Test of interest	Biopsy of primary NET and/or NET liver metastases	Studies that do not report histo-pathological biopsy results
Study design	Randomized controlled trials (RCTs)	Case reports
	Prospective and retrospective comparative cohort studies
Noncomparative cohort studies	Case-control studies	Reviews
	Case series
	Cross-sectional and/or cohort studies