ESTRO 2024 - Abstract Book

S2151

Clinical - Upper GI

ESTRO 2024

(i.e. V0.43Gy) of the lungs were compared. Statistical significance was determined with the Wilcoxon signed-rank test (p<0.05).

Results:

A total of 10 patients were enrolled, of whom 8 were diagnosed with distal esophageal cancer and 2 with gastroesophageal junction cancer. Among them, 3 patients presented with cN0, while 7 had a cN+ status. All patients underwent neoadjuvant chemoradiotherapy receiving 23 fractions of 1.8Gy. The CBCT image quality was considered sufficient to enable simulation of online adaptive workflow. Figure 1 and 2 present a comparison of DVH metrics between the baseline plan, the non-adaptive workflow, and the online adaptive workflow. Online adaptive radiotherapy significantly improved the coverage (D98%) of the ICTV compared to the non-adaptive workflow (p=0.002). Also, a significantly lower D0.1 cm 3 of the ICTV was observed, suggesting improved dose homogeneity (p=0.002). The MHD per fraction was reduced by 7.3% on average, from median 0.46Gy in non-adaptive radiotherapy to 0.43Gy in the adaptive radiotherapy workflow (p=0.084), corresponding with a reduction of the overall MHD from median 10.6Gy to 9.8Gy. Additionally, the volume of the heart receiving ≥1.3Gy per fraction (i.e. fraction-equivalent of V30Gy) was reduced from median 6.5% in non-adaptive to 4.0% in online adaptive radiotherapy (p=0.002). A significant average reduction of 7.9% was observed in the fractional MLD (median 0.30Gy to 0.28Gy, p=0.002) in the adaptive workflow compared to the non-adaptive workflow, corresponding with a reduction of the overall MLD from median 6.9Gy to 6.4Gy. Furthermore, the V0.87Gy and V0.43Gy of the lungs (i.e. fraction-equivalent of V20Gy and V10Gy) were significantly reduced from median 4.4% to 2.6% and from 24.9% to 17.9%, respectively (p=0.002 and p=0.006).