Prediction of Severe Lymphopenia During Chemoradiation Therapy for Esophageal Cancer : Development and Validation of a Pretreatment Nomogram

INTRODUCTION: In patients with esophageal cancer, occurrence of severe radiation-induced lymphopenia during chemoradiation therapy has been associated with worse progression-free and overall survival. The aim of this study was to develop and validate a pretreatment clinical nomogram for the prediction of grade 4 lymphopenia. METHODS AND MATERIALS: A development set of consecutive patients who underwent chemoradiation therapy for esophageal cancer and an independent validation set of patients from another institution were identified. Grade 4 lymphopenia was defined as an absolute lymphocyte count nadir during chemoradiation therapy of