Quantitative analysis of midline involvement for predicting contralateral cervical lymph node metastasis in supraglottic and glottic squamous cell carcinoma.

OBJECTIVE

To establish imaging-based quantitative indices for assessing midline involvement of laryngeal squamous cell carcinoma (LSCC) and guide surgical management of contralateral cervical lymph nodes according to tumor subsite and ipsilateral lymph node status.

METHODS

Retrospective analysis of midline-involved LSCC patients was conducted. For supraglottic LSCC, the maximum angle between the non-ipsilateral tumor margin and the midline was quantified; receiver operating characteristic (ROC) curve analysis was performed to identify the optimal cutoff value for predicting contralateral cervical lymph node metastasis. For glottic LSCC, the non-ipsilateral tumor-anterior commissure/arytenoid cartilage-anterior commissure ratio (T-AC/A-AC ratio) was calculated.

RESULTS

Among 58 supraglottic LSCC patients, 16 (27.6%) developed contralateral metastasis (cN0 occult 3.2%, cN + 27.3%). The optimal angle cutoff as 33.4° (AUC = 0.809, 95% CI: 0.690-0.928). Among 146 glottic LSCC patients, 5 (3.4%) had contralateral metastasis (cN0 occult 1.6%, cN + 8.3%). The T-AC/A-AC ratio was higher in the metastasis group, though the difference was not statistically significant (p = 0.06).

CONCLUSION

For midline-involved supraglottic LSCC, contralateral neck dissection (levels IIa and III) is recommended for cN0 patients with a margin-midline angle > 33.4°, while bilateral dissection is indicated for all cN+ patients. For midline-involved glottic LSCC, selective contralateral cervical dissection is mainly based on clinical evidence of contralateral metastasis. The quantitative imaging parameters (T-AC/A-AC ratio) require a larger sample size for validation.