The treatment guideline for locally advanced resectable oral squamous cell carcinoma (LAROSCC) is surgery + postoperative radiotherapy/chemoradiotherapy. Though the treatment is intensive with serious harm to quality of life, the survival of patients is poor. Neoadjuvant therapy has been evaluated in a number of clinical trials for LAROSCC, but failed to directly improve the overall survival. On the other hand, de-escalation of treatment followed by neoadjuvant is also been explored with some promising results. This study is to retrospectively include patients with LAROSCC who received neoadjuvant therapy and surgery. Survival between patients in two cohorts (cohort 1: received postoperative radiotherapy, cohort 2: received no postoperative radiotherapy) are to be compared.

Inclusion Criteria:

• Patients receiving neoadjuvant therapy and surgery for oral squamous cell carcinoma from January 2008 to December 2021
• Oral squamous cell carcinoma histology (including tongue, gingiva, cheek, floor of mouth, hard palate and posterior molar area)
• Clinical stage III/IVA (T1-2/N1-2/M0 or T3-4/cN0-2/M0, AJCC 2018) for the primary lesion
• Surgical resection samples that can be evaluated for pathological remission rate

Exclusion Criteria:

• Severe/active systemic disease
• Previously radiotherapy or neck lymph node dissection for the head and neck region
• Evidence of tumor recurrence or metastasis in physical examination or imaging (ultrasound, CT, MRI) before initiation adjuvant radiotherapy
• Evidence of severe/unrelieved side effects of neoadjuvant therapy or severe postoperative complications before initiation adjuvant radiotherapy

Oral squamous cell carcinoma (OSCC) patients received neoadjuvant therapy and surgery with and without postoperative radiotherapy in the Department of Oral and Maxillofacial-Head and Neck Oncology in Ninth People's Hospital, Shanghai JiaoTong University School of Medicine from January 2008 to December 2021.