The predictive value of tumor depth of invasion for contralateral neck disease in tongue cancer.

Objective: Management of the contralateral cN0 neck in well-lateralized oral tongue squamous cell carcinoma (OTSCC) is controversial. Depth of invasion (DOI) is a strong predictor of ipsilateral nodal metastases. This study examines if DOI can predict contralateral neck disease (CND).

Methods: A retrospective analysis was performed on patients treated with primary surgery for lateralized OTSCC at a single tertiary care academic institution from 2014 to 2021. Multivariable analysis was performed to assess the relationship between DOI and CND.

Results: 155 patients were included. 101 (65.2%) patients had T1/T2 disease, while 54 (34.8%) had T3/T4 disease. 22 (14.2%) patients had CND. Mean DOI of patients with CND and without CND was 21.0 mm and 9.8 mm (p < 0.001), respectively. Univariable regression models showed higher DOI was associated with increased risk of CND overall (OR = 1.11, 95% CI: 1.06, 1.17, p < 0.001), in patients with T1 disease (OR = 1.38, 95% CI: 1.11, 2.20, p = 0.038), and in patients with cN0 disease (OR = 1.09, 95% CI: 1.01, 1.17, p = 0.028). Multivariable regression model confirmed higher DOI was associated with increased risk of CND (OR = 1.09, 95% CI: 1.04, 1.16, p = 0.001). A DOI of 6 mm was identified as a potential threshold for increased risk of CND.

Conclusions: DOI was identified as a predictive factor for CND in OTSCC. At the time of ipsilateral neck dissection, a DOI ≥ 6 mm may represent a threshold associated with an increased risk of CND, indicating that contralateral neck management could be considered.