Main characteristics of eligible studies.

CUP: carcinoma of unknown primary; HCC: hepatocellular carcinoma; Mix: mixed treatment including chemotherapy, hormonal therapy, surgery, radiotherapy, and supportive care; MPM: malignant pleural mesothelioma; NA: not available; NR: upper value not reached; NSCLC: non-small cell lung cancer; RCC: renal cell carcinoma; RFA: radiofrequency ablation; SCCE: small cell carcinoma of the esophagus; TACE: transcatehter arterial chemoembolization. *The numbers of patients died or lost during the follow up were recorded in parentheses.