Preoperative radiotherapy in gastric cancer: CTV definition for conformal therapy according to tumor location

In the past radiation oncologists had not a major interest in the treatment of gastric cancer, but the positive outcomes of the Intergroup Study (INT-0116) supported the role of locoregional control in promoting better survival. To reduce the toxicity and the risk of residual disease in locally advanced tumors after surgery,a preoperative approach was tentatively considered. The aim of this manuscript is to define the location of nodal area at risk for cancer involvement according to the tumor location (cardias, corpus, antrum) on CT images to help the radiotherapist in the contouring process of the CTV for preoperative conformal treatment of gastric cancer. The analysis of both the percentage of nodal involvement detected at surgery and of the site of recurrence after radical surgery can direct to the areas to be considered at risk with its contouring on CT. Preoperative conformal-three dimensional radiotherapy of gastric cancer requires clear and well defined contouring guide-lines to allow the evaluation of clinical outcomes and the analysis if the area at risk for recurrence has changed after the preoperative approach.