Comparing treatment plans for proximal and middle/distal stomach cancer: intensity-modulated radiotherapy, volumetric-modulated arc therapy, and tomotherapy

Background: Adjuvant chemoradiotherapy is viewedas a definitive treatment after resection of stomach cancer (SC). To protectnormal tissue, several highly conformal radiotherapy modalities evolved.Therefore, we aimed to compare dosimetric parameters of helical tomotherapy(TOMO), volumetric-modulated arc therapy (VMAT), and intensity-modulatedradiotherapy (IMRT) in the adjuvant treatment of SC in different locations. Methods: This retrospective study wasconducted from January 2013 to May 2017 and included 11 patients with gastriccancer receiving adjuvant chemoradiotherapy after total gastrectomy. Both IMRTand VMAT plans were generated on the Pinnacle treatment planning system andTOMO plans were generated using a helical tomotherapy system. Adjuvantradiotherapy was prescribed with a total radiation dose of 50.4 Gy in 28fractions. Results: In proximal SC, TOMO achieved asignificantly lower dose for the heart, total kidney, left kidney, and liverthan that of IMRT or VMAT (P<0.05). In middle/distal SC, lower total kidneymean dose and V20 were observed with TOMO compared with IMRT (P=0.010 and0.011, respectively) and VMAT (P=0.049; P=0.014). Conclusions: For the adjuvant treatment of gastriccancer, TOMO not only provided superior dose sparing for total kidney, leftkidney, liver V 20 and liver V 30 in patients with proximalgastric cancer but also significantly lowered the heart dose in proximal SCwhen compared to IMRT or VMAT plan.