Feasibility of intensity-modulated radiation therapy with concurrent chemotherapy in patients with Siewert type II and adenocarcinoma of the esophagogastric junction before surgery

Objective: To analyze the feasibility of intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy in patients with locally advanced Siewert type II and III adenocarcinoma of the esophagogastric junction (AEG). Methods: A prospective study was performed on 45 patients with locally advanced Siewert type II and III AEG. These patients received two cycles of XELOX chemotherapy and concurrent IMRT to the involved field (45 Gy/25 f, 5 f/week) for 6 to 8 weeks before surgical resection. The patients ingested 800 to 1000 ml water to distend the stomach before computed tomography (CT) scan. The gross tumor volume of the primary tumor (GTV-t) was delineated on the CT image with a stomach wall thickness of > 5 mm. GTV-t was expanded by a 2.0 cm margin along the esophagus, a 1.5-2.0 cm margin along the stomach, and a 0.8 cm margin axially outward to generate the clinical target volume of the primary tumor (CTV-t). GTV-lymph node (GTV-nd) was delineated based on CT/magnetic resonance imaging scan. CTV-nd only included GTV-nd and the involved lymph nodes. Planning target volume was generated by expanding the CTV by 0.8 to 1.0 cm. The feasibility of target volume delineation was explored by analyzing postoperative pathological examination results and radiotherapy toxicities. Results: All the 45 patients completed preoperative concurrent chemoradiotherapy and surgery, with two cycles of chemotherapy in 39 patients and one cycle in 6 patients. The rates of R_o resection and pathological complete response (pCR) were 95.6% (43/45) and 22.2% (10/45), respectively. There were 10 (22.2%), 17(37.8%), 15 (33.3%), and 3(6.7%) patients with tumor regression grades 0, 1, 2, 3, respectively. The rate of lymph node metastasis was 37.8%(17/45), and the lymph node ratio was 4.33% (46/1062). The postoperative pathological examination showed that T and N downstaging after surgery was observed in 24 and 26 patients, respectively;the proportions of patients with T₃-T₄ tumors and positive lymph nodes after surgery declined by 51.1%(P = 0.000) and 42.2%(P = 0.000), respectively. The overall incidence of radiation esophagitis/gastritis was 44.4%(20/45), and the incidence rates of grade 1, 2, and 3 radiation esophagitis/gastritis were 18%, 22%, and 4%, respectively. The incidence of acute radiation pneumonitis was 6.7%(3/45), all in grades 1 and 2. There was one perioperative treatment-related death. Conclusions: Two cycles of XELOX chemotherapy combined with concurrent 45 Gy radiotherapy before surgery in patients with locally advanced Siewert type II and III AEG can achieve a relatively high pCR rate, effectively reduce the lymph node metastasis rate, achieve downstaging, and increase R₀ resection rate. This regimen has many good advantages, including low incidence of acute toxicities, good tolerability, and acceptable rate of perioperative treatment-related deaths. The target volume delineation involving metastatic lymph nodes is feasible. (authors)