ESTRO 2022 - Abstract Book

S609

Abstract book

ESTRO 2022

In Figure 2A, hazard ratios are reported at the 90th percentile of SD dose and peritumour density across patients, as hazard can only be interpreted at specified values of the interacting variable. The result demonstrates that higher density is associated with risk of LR for non-uniform dose outside the GTV. The dose required to this region (Fig. 1A) is not yet known, but example stratification is shown (Fig. 2B and C). Dose SD outside the GTV only weakly correlates with tumour dose, and instead reflects PTV heterogeneity and sharp dose fall-off ( data not shown ).

Conclusion This study confirmed an interaction between peritumour density and incidental dose that predicts LR regardless of cohort differences. We validated that LR risk can be stratified on peritumour density and is increased for patients with non-uniform