Dose-dependent Effects of Unintended Splenic Irradiation After Neoadjuvant Radiochemotherapy for Esophageal Cancer.

BACKGROUND/AIM:The aim of this study was to investigate the relationship between radiation exposure to the spleen, dose-dependent organ changes, and their possible influence on clinical and oncological outcome. Furthermore, to provide evidence and sensitivity for considering the spleen as an relevant organ at risk. PATIENTS AND METHODS:A total of 93 patients with carcinoma of the distal esophagus or gastroesophageal junction were selected for this retrospective study. Changes in spleen volume, infections, and oncological outcome were assessed during follow-up using linear and logistic regression models. RESULTS:Spleen volume decreased significantly by a median of 27.5 ml to an absolute value of 178.1 ml (p<0.001) within twelve months. Statistical analyses revealed a significant association of infectious events with worse progression-free survival (PFS) (p=0.002) and overall survival (OS) (p=0.001). With a mean spleen dose <4 Gray, both OS and PFS were also significantly prolonged. CONCLUSION:A decrease in spleen organ volume after neoadjuvant radiochemotherapy was demonstrated with a consecutive increased incidence of infectious events, significantly correlating with worse PFS and OS.