National statistics about resection of the primary tumor in asymptomatic patients with Stage IV colorectal cancer and unresectable metastases. Need for improvement in data collection. A systematic review with meta-analysis

•Patients with Stage IV colorectal cancer and not resectable metastases represent a heterogeneous group.•A review of data analyses demonstrates that there are many missing data to draw meaningful conclusions.•Improvement in National data collection may represent the ground for a proper assessment of.