2.1 Search strategy
Searches were conducted in April 2020 in three publicly available databases: PubMed; Google Scholar; and Cochrane Library. Search strategy involved an iterative process in which keywords for searches were a combination of one diagnosis name and one topic name. The Ewing sarcoma family tumors (ESFT) historically included a family of morphologically similar malignancies but with diverging names. Thus, five diagnosis search terms were utilized: Ewing sarcoma; Ewing’s sarcoma; Peripheral Neuroectodermal Tumor; PNET; and Askin Tumor. Alongside a diagnosis term, 13 topic search terms were utilized: bone marrow; bone marrow biopsy; bone marrow aspirate; Positron Emission Tomography; PET; metastatic; metastatic pattern; metastasis; randomized; phase III; clinical trial; staging; and diagnosis. This process resulted in 65 individual searches (5 diagnosis terms x 13 topic terms) for each of the 3 databases utilized (195 total searches across all databases). For each search, a single reviewer documented the number of results, the number of abstracts read and the number of articles meeting criteria to be shared with a second reviewer for final approval. A third reviewer was available to resolve any discrepancies. Searches resulting in >500 results were edited to restrict specific keywords deemed irrelevant to this study. For example, the PubMed search of ‘Primitive Neuroectodermal Tumor’ + ‘metastatic’ yielded 4,129 results. After designating the search not return articles with keywords ‘case report,’ ‘neuroblastoma,’ ‘medulloblastoma,’ and ‘pancreatic,’ results decreased to 284 articles. To expand our search, references of the retrieved articles were also screened for additional studies.