Adjuvant chemoradiotherapy for gastric carcinoma: dosimetric implications of conventional gastric bed irradiation and toxicity.

Abstract

AIMS: Recently, a survival advantage has been shown using adjuvant chemoradiotherapy after complete resection of gastric cancer. If survival advantages are to be maintained, treatment-related complications must be minimised. In this study, we explored the dosimetric implications and toxicity of conventional large field gastric bed irradiation. MATERIALS AND METHODS: Between 2000 and 2002, 16 patients received adjuvant 5-fluorouracil (5-FU) chemoradiotherapy after complete resection of gastric cancer. Radiotherapy was simulator planned using anterior-posterior parallel opposed fields to 45 Gy in 25 daily fractions over 5 weeks. RESULTS: Thirteen patients (81%) completed radiotherapy and eight patients (50%) completed chemotherapy as planned. Toxicity was the main factor for discontinuation. Substantial dose inhomogeneities were shown using retrospective computed tomography recreation of dose-volume histograms (DVHs) of the organs at risk. CONCLUSIONS: Although the delivery of chemoradiotherapy using conventional two-dimensional simulator planning is a feasible technique, significant under-appreciation of dose inhomogeneity exists. Conformal computed tomography planning is vital to document doses received by organs at risk, especially the spinal cord and kidneys, which may receive high doses, and prospectively correlate these with acute and long-term toxicity in order to redefine organ at risk tolerances in the setting of chemoradiation.