Notch Intracellular Domain (NICD) Expression and Clinical Manifestations of Second Primary Tumor at Esophagus in Patients with Head and Neck Squamous Cell Carcinoma.

Active smoking and alcohol use were found to be significantly associated with SPT development. A high percentage of NICD inactivation was noted in HNSCC with no significant difference between groups. The Notch signaling pathway is involved in HNSCC tumorigenesis, but may not be a suitable molecular marker for SPT development.