C5AR1 and neoplasm: Against this background, the objective of the present study was to evaluate C5aR1 expression by immunohistochemistry in a broad panel of non-neoplastic and neoplastic human tissue samples from routine pathology to obtain a broad expression profile of C5aR1 in these tissues and to provide a basis for more in-depth investigations with regard to diagnostic or therapeutic interventions also in tumour entities not investigated in this respect so far.