Embase.com:: 'metastasis'/exp OR metasta*:ab,ti OR advanced:ab,ti;; Cochrane Library:: metasta* or advanced:ti,ab,kw;; PubMed:: "Neoplasm Metastasis"[Mesh] OR metasta*[tiab] OR advanced[tiab];; PubMed variant:: "Neoplasm Metastasis"[Mesh] OR metast*[tiab] OR micrometast*[tiab] OR seeding*[tiab] OR circulat*[tiab] OR spread*[tiab]