Predictors of Distant Metastasis after Radical Surgery Followed by Postoperative Radiotherapy with or without Chemotherapy for Oropharyngeal Cancer

PURPOSE: We investigated the prognostic factors for distant metastasis (DM) in patients with locally advanced oropharyngeal cancer (OPC) treated with surgery and adjuvant radiotherapy with or without concurrent chemotherapy. MATERIALS AND METHODS: F-FDG PET-CT) were evaluated, and their influence on DM and survival outcomes were analyzed. RESULTS: Median follow-up period was 48.0 months. Recurrence was observed in 20 patients, including locoregional recurrence and DM. DM was observed in 13 patients. A multivariate analysis confirmed that the presence of lymphovascular invasion (p=0.031), lower neck lymph node (LN) involvement (p=0.006), SUVmax ≥ 9.7 (p=0.014), and tumour size ≥ 3 cm (p=0.037) significantly affected DM. HPV status was not associated with DM. Perineural invasion (p=0.048), lower neck LNinvolvement (p=0.008), SUVmax ≥ 9.7 (p=0.019), and tumour size ≥ 3 cm (p=0.033) were also significant factors for the DM-free survival rate. CONCLUSION: F-FDG PET-CT, and large tumour size were predictive factors for DM in patients of OPC.