Recurrence Risk in Lateralized Floor of Mouth Carcinoma: Depth of Invasion Versus Midline Distance
Jannik Ketschau, Alex Grabenhorst, Hannes Singer, Helena Kram, Nils Krautkremer, Cornelius Leopold, Jonathan Mohr, Katharina Pippich, Klaus‐Dietrich Wolff, Chaim Ohayon, Lucas M. RitschlABSTRACT
Background
Contralateral nodal recurrence in lateralized floor‐of‐mouth squamous cell carcinoma (OSCC) remains difficult to predict, and objective preoperative parameters to guide contralateral neck management in tumors without midline crossing are lacking.
Methods
This retrospective cohort study included 97 patients with lateral floor‐of‐mouth OSCC treated by surgical resection and neck dissection. Depth of invasion (DOI) was evaluated using endpoint‐specific univariable Cox regression. Contralateral nodal disease was analyzed in patients without midline crossing ( n = 68) using a composite endpoint of occult contralateral nodal metastasis and/or subsequent contralateral nodal recurrence. Tumor‐to‐midline distance was assessed on standardized multiplanar preoperative CT or MRI.
Results
DOI was associated with local recurrence (HR 1.322 per mm, 95% CI 1.131–1.545, p < 0.001) and ipsilateral regional recurrence (HR 1.199, 95% CI 1.052–1.367, p = 0.007), but not with contralateral recurrence (HR 1.030, 95% CI 0.834–1.272, p = 0.782). Among 68 patients without midline crossing, no occult contralateral metastases were identified in 19 clinically contralateral node‐negative patients undergoing elective contralateral neck dissection. Four patients (5.9%) developed subsequent contralateral nodal recurrence. Midline distance was smaller in patients with an event (median 3.15 vs. 6.40 mm; p = 0.022; AUC 0.845). All four events occurred at < 5 mm (4/21 [19.0%] vs. 0/42 [0%]; Fisher p = 0.010). In time‐to‐event analysis, greater midline distance was associated with a lower hazard of contralateral recurrence (HR 0.622 per mm, 95% CI 0.395–0.981, p = 0.041).
Conclusion
DOI showed an outcome‐specific association with local and ipsilateral, but not contralateral, recurrence. In tumors without midline crossing, quantitative proximity to the midline was associated with subsequent contralateral nodal failure. The observed 5‐mm threshold is exploratory and requires external validation before it can inform clinical decision‐making.