Clinical Target Volume Definition in Preoperative Radiotherapy of Rectal Carcinoma: a Systematic Review

Purpose of Review: Preoperative radiotherapy (RT) or chemoradiation represents a standard option in neoadjuvant treatment of rectal cancer (RC). The aim of this analysis is to present a systematic review of clinical target volume (CTV) definition in preoperative RT of RC. A systematic review of published literature was performed. Studies providing clear indications for CTV definition in preoperative RT of RC were eligible. Only studies published as full text were considered. The search was restricted to English, German, and French languages. The CTV delineation, based on the different guidelines, was drawn on selected slices of a CT scan and the CTV definition based on different guidelines was reported in a table to facilitate the comparison. Recent Findings: A total of six publications containing indications for CTV delineation fulfilled the selection criteria and were included in our review. The studies showed a large variability in available indications between CTV contouring guidelines of RC, partly arising from differences in methods used to propose the single guidelines: expert opinion, systematic review, computer-generated consensus, and 3D modeling of recurrence sites. Summary: In our systematic analysis, the available indications for CTV definition in preoperative RT of RC were reviewed. A large variation in target volume delineation was observed.