Patterns and characteristics of metachronous distant metastases in patients with oral squamous cell carcinoma - A cohort analysis.

OBJECTIVES: Distant metastases (DMs) are a significant prognostic factor in oral squamous cell carcinoma (OSCC). This study analyzed the pattern and predictors of metachronous DMs (MDMs) over time in a large OSCC cohort treated with curative intent. MATERIALS AND METHODS: A total of 1,122 patients with primary OSCC were treated at the University Medical Center Hamburg-Eppendorf between 2009 and 2019. After excluding patients with synchronous metastases or palliative treatment, 1,040 patients remained for analysis. RESULTS: Of these, 93 patients (8.94%) developed MDMs. The lungs were the most frequent site (n = 64), followed by bone (n = 26), thoracic lymph nodes (n = 19), and liver (n = 17). The estimated mean time to MDM was approximately 430 days. In patients with late-onset metastasis (≥ 24 months), the lung was most often the sole site involved. Multiple metastatic sites were observed in 40.86% of cases. Cox regression analysis identified several independent factors associated with early metachronous dissemination (≤ 12 months after diagnosis): pN2c nodal status (HR 10.778, 95% CI 1.123-103.405, p = 0.039), age < 60 years (HR 3.626, 95% CI 1.048-12.547, p = 0.042), and treatment with surgery plus adjuvant radiochemotherapy (HR 20.025, 95% CI 1.954-205.232, p = 0.012). CONCLUSION: The occurrence of MDMs was observed in around 10% of OSCC patients. Early metachronous dissemination was associated with pN2c, age < 60 years and combination therapy. CLINICAL RELEVANCE: These findings support a time- and pattern-dependent model of distant dissemination in OSCC and may inform risk-adapted surveillance and treatment strategies.