Dosimetric comparison and time consuming evaluations for neoadjuvant 5-fields versus 7-fields Intensity-Modulated Radiation Therapy for locally advanced rectal cancer.

Preoperative – multidrug - chemoradiotherapy schedule (PCR) is proven to be the standard approach in patients with locally advanced rectal cancer (LARC). The main limiting factor of PCR delivery is severe acute gastrointestinal (GI) toxicity due to the small bowel irradiated volume. Compared to 3-dimensional conformal radiation therapy (3DCRT), intensity-modulated radiotherapy (IMRT) plans, with 7 or more fields, by highly conformal dose distributions, will minimize the dose received by small bowel, but required an increase in overall treatment time. The purpose of this study was to investigate if simple IMRT plans were comparable to conventional 7-fields IMRT in terms of dose distribution, with the advantage of reducing time delivery.