Defining the optimal threshold and prognostic utility of pre-treatment hemoglobin level as a biomarker for survival outcomes in head and neck cancer patients receiving chemoradiation

•The optimal threshold of anemia for head and neck cancer patients is unclear.•Threshold of anemia was determined to be hemoglobin of 11.4.•Anemia was associated with worse overall and progression-free survival outcomes.•Anemia was prognostic for survival among patients with HPV-negative tumors.