Abstract: Background and purpose: Oral malignant melanoma (OMM) is extremely aggressive and has a poor prognosis. Tumor recurrence or metastasis is still found in many long-term survival cases. The objective of this study was to investigate the clinical characteristics of patients with long-term survival of OMM and analyze its correlation with prognosis. Methods: This was a retrospective cohort study, and data of relapsed OMM patients with an overall survival of >60 months were collected. Predictor variables included sex, age, anatomic site, pigmentation history, tumor type, tumor size, biopsy type, satellite lesions, TNM-staging status and effective treatment. Event-free survival (EFS) and survival after relapse were used as survival analysis. Results: A total of 106 patients were enrolled, 66% (70/106) of whom suffered local recurrence. New pigmentations occurred in 86% (60/70) of relapsed OMM patients, and most of them (82%) were aggressive. TNM-staging status (P=0.03) and treatment mode (P=0.005) were associated with survival after relapse.TNM-staging status (P=0.03) and biopsy type (P<0.0001) were independent and poor prognostic factors for EFS. Conclusion: New oral pigmentations are the most common recurrent type of OMM patients, which need to be frozen or have extended resection as soon as possible; compared with surgical extended resection, cryotherapy is simple with less trauma, and can improve the quality of life.

Key words: Oral mucosa, Melanoma, Relapse, Cryotherapy