Table 2.

Eligibility criteria for review on Ki67 index.

Study characteristics	Inclusion criteria	Exclusion criteria
Participants/population	Patients with primary neuroendocrine tumors who were assessed with Ki67 index, mitotic count or tumor grading	Patients over the age of 18 years old
Tumor markers	Tumor markers (Ki67 index, mitotic count or tumor grading) must be obtained from the primary tumor	Studies that do not report the predictive value of Ki67 index, mitotic count or tumor grading
Study design	Follow-up studies for the development of liver metastases	No follow-up studies for the development of liver metastases
	Randomized controlled trials (RCTs)
	Prospective and retrospective comparative cohort studies	Case reports
	Noncomparative cohort studies
	Case-control studies	Reviews
	Case series