Frequency, predictors, and prognostic impact of intraparotid lymph node recurrence in oral cavity squamous cell carcinoma: a retrospective case-control study.

BACKGROUND: Intraparotid lymph node (PLN) recurrence from oral cavity squamous cell carcinoma (OCSCC) is uncommon and inadequately characterised, with limited literature regarding its frequency, predictors, and prognostic implications. METHODS: A retrospective analysis was conducted on consecutive patients with OCSCC who underwent upfront surgery at a tertiary care centre from 2022 to 2024. Patients with clinical or radiological evidence of PLN recurrence were identified. A site-matched cohort of 100 consecutive patients with OCSCC treated surgically during the same time frame, and patients with non-PLN recurrences served as controls. RESULTS: Among 939 surgically treated OCSCC patients, 22 (2.34%) developed PLN recurrence. Parotid recurrences occurred early, with a median time to detection of 3 months (range, 2-13 months). Presence of greater than 4 metastatic lymph nodes was the only independent predictor of PLN recurrence (OR 5.78, 95% CI 1.43-23.28; p = 0.0136). Patients with PLN recurrences demonstrated significantly inferior survival outcomes. Compared with patients with recurrence outside PLN, patients with PLN recurrences had a higher incidence of tumour location in the gingivobuccal complex, skin involvement, lymphovascular invasion, close margins and belonging to stage IVb. Recurrence in the PLN portends poor OS compared to recurrence outside PLN (HR: 1.98, 95% CI:0.99 to 3.94), with successful salvage possible in only 1 out of 22 patients in the former compared to 9 out of 46 in the latter. CONCLUSION: Greater than 4 metastatic cervical lymph nodes, location in the gingivobuccal complex, skin involvement, stage IVb, lymphovascular invasion, and margins less than 5 mm are predictors of failure in the PLN.