Flowchart of patients’ enrollment.

The patients’ data were obtained from a single institution during a period between August 2014 and March 2016. We retrospectively reviewed the data and retrieved data of oral cancer patients (n = 453). We excluded patients with recurrent or secondary oral cancers, or those with other malignancies (n = 68). Patients with poor performance status (ECOG ≥ 3), liver cirrhosis, renal failure or poor heart or lung function, or who were unfit for flap reconstruction surgery, were also excluded to reduce bias and confounding factors (n = 50). Incomplete or missing medical records were excluded (n = 4). Finally, a total of 331 patients (190 male, 141 female) with primary oral cancer who received curative surgery and flap reconstruction were studied. (RAR)