IMRT-SIB and Capecitabine in Preoperative Rectal Cancer Treatment

RATIONALE: Using small radiation beamlets of different intensity, IMRT (intensity modulated radiation therapy) allows shaping the dose around planning target volume with better sparing of normal tissue comparing to 3D conformal radiotherapy. It allows daily delivery of higher dose to the tumor with simultaneous integrated boost (SIB), consequently shortening total treatment time with potentially better response to treatment. In advanced rectal adenocarcinoma excellent response to preoperative radiochemotherapy with complete eradication of the primary tumor observed in the histopathological specimen (pathological complete response, pCR) correlates with a favorable overall prognosis, so trying to achieve better response to preoperative treatment with higher pCR seams feasible. PURPOSE:The hypothesis of this study is that in preoperative radiochemotherapy for locally advanced rectal adenocarcinoma shortening of the total treatment time with IMRT-SIB to 22 daily fractions concomitant with capecitabine results in an improved pCR rate from 9% (Slovenian trial) to 25%. Secondary objectives are to evaluate pathological down-staging rate, histopathological R0 resection rate, sphincter preservation rate, perioperative surgical complication rate, local control, disease-free survival (DFS), overall survival (OS), late toxicity and quality of life.