ESTRO 2024 - Abstract Book

S5981

RTT - Treatment planning, OAR and target definitions

ESTRO 2024

The characteristics of the patients included in this in silico planning study are listed in Table 1. In the hypoCROSS plans, the mean heart dose (MHD), mean lung dose (MLD) and mean spleen dose (MSD) were significantly lower compared to the CROSS plans. The differences were however relatively small; on average 6.4% (MHD), 4.7% (MLD) and 7.8% (MSD). As hypothesized, the total BOT was significantly lower in the hypoCROSS plans and reduced on average by 15.7% (139 vs. 117 minutes; p<0.01). In the hypoCROSS plans, patients with high BOT (>120min (median)) had significantly higher N-stage (p=0.02), compared to patients with a low BOT (Table 1).

Conclusion:

Hypofractionation, 18 x 2.2Gy RBE , is associated with reduced beam on time and, to a lesser extent, reduced mean dose to heart, lungs and spleen in the treatment of esophageal cancer patients. Both these factors are expected to have a positive impact on radiation-induced lymphopenia.