The concept of intensity-modulated and image-guided radiotherapy (IMRT-IGRT) with a simultaneous integrated boost (SIB) by the TomoTherapy Hi-Art II System in preoperative RT of rectal cancer was implemented in our department. Two pilot studies demonstrated its ability to minimize the setup margin, which led to a significant decrease in the irradiated volume of small bowel and bladder. Besides, this technique allows the delivery of a SIB in patients at high-risk for local failure, this as an alternative strategy to the concomitant administration of chemotherapy. The synergism of improved dose distributions by IMRT and correction of daily treatment uncertainties by IGRT resulted in a limited acute toxicity profile and promising local control in a phase II study with a total accrual of 108 locally advanced rectal cancer patients. Finally, the implementation of this novel modality appeared to be attractive in inoperable oligometastatic colorectal cancer, by displaying a promising response rate and limited toxicity in a phase II trial. (BELG J MED ONCOL 2012;6:70–72)