Participants
All adult (age > 18) patients with advanced (T4a or
T4b) OCSCC diagnosed from 2007 to 2016 were included. 2007 was chosen as
a starting point for our population based on the timing of SEER’s
collection of information on patient insurance status. Patients were
identified based on combinations of variables including tumor histology
-squamous cell carcinoma and its variants (basaloid, papillary, spindle
cell, verrucous), primary site – mucosal lips (C000-C006, C008-C009);
oral tongue (C020-C024, C028-C029); floor of mouth (C040-C049); and gum
and other mouth (C030-C039, C050-C059, C060-C069)], and stage- T4,
T4a, and T4b. Tumors of the base of tongue and any subsite that included
or overlapped with the oropharynx were excluded to prevent confounding
or effect modification by human papillomavirus virus (HPV) infection.
The following exclusion criteria were used: patients with unknown
demographic information including sex, age at diagnosis, race, and
marital status; patients with unknown clinical information including
histologic grade, AJCC Tumor, Node, Metastasis (TNM) stage; patients
with no information on definitive surgery or radiotherapy; and patients
with metastatic disease at initial presentation.