Fig. 2

Postoperative chemotherapy showed significant survival improvement on RFS (a) and OS (b) in the whole cohort of patients, and on RFS (c) and OS (d) in the patients without PNI. However, it did not showed any improvement on RFS (e) or OS (f) in the patients with PNI. PNI, perineural invasion; RFS, recurrence free survival; OS, overall survival