Fig. 4

Flow chart of the search, selection, and inclusion processes for the systematic review of the literature. An example PubMed search equation: ((“spleen”[MeSH Terms] or “spleen”[all fields] or “splenic neoplasms”[MeSH terms] or “splenic metastasis”[all fields]) and (“neoplasm metastasis”[MeSH Terms] or (“neoplasm”[all fields] and “metastasis”[all fields]) or “neoplasm metastasis”[all fields] or “metastasis”[all fields])) and (“nasopharynx”[MeSH terms] or “nasopharyngeal neoplasms”[MeSH terms] or “nasopharynx”[all fields] or “nasopharyngeal”[all fields])