NRP1 and osteosarcoma: Additional reports from studies conducted in different tumor types revealed that NRP1 overexpression was directly related to the presence of distant metastasis [40,47,48], advanced stages [47,48], invasion depth and lymph node metastasis in gastric cancer [40], osteosarcoma [47] and nasopharyngeal carcinoma [48], thus supporting results obtained in the present meta-analysis.