The goal of this observational study is to test the expression levels of salivary and plasma exosomal miR-185 in patients with oral leukoplakia and oral squamous cell carcinoma. The main questions it aims to answer are:

• Is it possible to identify the cancer risk of oral leukoplakia in its early stages by detecting salivary and plasma exosomal miR-185?
• Is it possible to monitor the cancer risk of oral leukoplakia and the prognosis of oral cancer using salivary exosomal miR-185?

Participants will be asked to:

• Cooperate with the investigators in completing the oral examination.
• Take saliva and plasma before the biopsy surgery.
• Perform the biopsy surgery following the usual diagnostic procedures.
• Attend regular follow-up appointments (every 3 months) for the duration of the study.

The first part of the study is a cross-sectional study in which the investigators will detect the expression level of salivary exosomal miR-185 in the participants at a single time point. The second part of the study is a prospective cohort study, in which the investigators will conduct regular follow-ups on the participants enrolled in the first part.

Inclusion Criteria:

• Males or females aged 30~80 years.
• Clinical diagnosis consistent with oral leukoplakia and oral cancer.
• Individuals with local stimulating factors correlated with oral lesions (including residual roots, residual crowns, poor oral restorations, cheek biting, and tongue biting habits).
• Oral lesions not subjected to any treatment, including laser, photodynamic therapy, radiotherapy, and chemotherapy.

Exclusion Criteria:

• Pathological diagnosis of another disease rather than oral leukoplakia or squamous cell carcinoma.
• Females who were pregnant or breastfeeding.
• Individuals who had malignancy, severe and precariously controlled diabetes mellitus, episodes of cardiovascular disease, hepatic or renal dysfunction, respiratory disease, hematologic disease, or immune abnormalities in the past year.
• Individuals with a psychiatric disorder.
• Other conditions deemed inappropriate for study participation by the researchers.

Participants were from the Department of Stomatology, Beijing Stomatological Hospital, Capital Medical University, Beijing, China.

Data on participants' gender, age, disease duration, lesion characteristics (location and size), tobacco, alcohol and betel nut consumption habits, histopathologic diagnosis, and miR-185 levels in saliva and plasma exosomes will be shared.

1 years after publication of all results.

Share data in a standardized format adhering to unified standards. The data should be comprehensive, trustworthy, traceable to the source, timely, and gathered and processed using consistent methods. Furthermore, anonymity of participants' identity information is required.

Applicants seeking permission to access the data must clearly specify the intended purpose of use. Access to the data will only be granted to authorized individuals who have executed a data use agreement with the investigators. Any unauthorized sharing of data or use of the data for commercial purposes is strictly forbidden.

Project Director Xiaobing Guan will be responsible for reviewing data access requests.