MALAT1 and osteosarcoma: Among all 10 included studies, diverse outcome measures (tumor weight, tumor volume, or both of them); diverse lncRNA types (HOTAIR, MALAT1, PVT1,TUG1, and so on) or functions (oncogenes or tumor suppressors) of lncRNAs; various osteosarcoma cell lines used to produce osteosarcoma xenograft models (MG-63, U2 OS or MNNG/HOS cells) and different methods of producing xenograft models (subcutaneous inoculation or peritoneal metastasis model) were all reported.