Case presentation: the effect of volumetric image guidance and adaptive radiotherapy on cardiac dose in a patient with esophageal cancer

Abstract

We present the case of a patient with esophageal cancer whose tumor size regression prompted re-planning to decrease the cardiac dose. A 68-year-old male presented at our outpatient clinic with dysphagia. He was diagnosed with clinical T3N1 M0 adenocarcinoma located at the distal esophagus-esophagogastric junction. He was decided to have surgery after receiving neoadjuvant chemoradiotherapy. Following 4-D CT simulation, IG-IMRT with SIB technique was planned as 50 Gy in 25 fractions to iGTV and as 45 Gy to the area identified as the CIV. Daily kV and weekly CBCI were planned at the beginning of the treatment. Concurrent CT with weekly paclitaxel-carboplatin was administered. At the simulation and start of the treatment, the heart was pushed anteriorly due to the mass effect and dilatation in the mid-lower esophagus. The mass and dilatation regressed at the weekly CBCT of the patient. The third-week CBCT evaluation revealed the movement of the heart posteriorly into the PTV. Re-simulation was performed to continue with the adaptive planning for the last 10 treatment fractions. The cumulative dose received by the heart was reduced from 96% to 93% for V5Gy, from 79% to 60.8% for V10Gy, from 60% to 43.2% for V15Gy, from 35% to 21% for V20Gy, and from 29.6 to 28 Gy for the mean cardiac dose with the volumetric image-guided adaptive planning. If tumor regression is predicted during radiotherapy to possibly change doses of organs at risk, volumetric image guidance should be encouraged once per week, at least, to consider adaptive treatment when required to ensure the critical organ doses within safe limits.