MR imaging predictors of local control of glottic squamous cell carcinoma treated with radiation alone.

PURPOSE To retrospectively evaluate the prognostic significance of magnetic resonance (MR) imaging-determined tumor parameters, especially the presence of cartilage invasion, regarding local control of glottic squamous cell carcinoma treated with radiation therapy (RT) alone. MATERIALS AND METHODS The study was performed with the approval of our institutional review board; direct patient consent was waived. Pretreatment MR images of 118 patients aged 41-86 years (110 men, eight women) with glottic carcinoma treated with RT alone were reviewed for tumor involvement of specific laryngeal anatomic subsites (including laryngeal cartilage), tumor volume, and extralaryngeal tumor spread; these findings were compared with local control. Local control was defined as absence of a recurrence at the primary site for 2 years. Statistical significance of differences between curves for local control estimated with the Kaplan-Meier method was tested with log-rank test. RESULTS Results of univariate analysis showed all MR imaging-determined parameters to be significant predictors of local control rate, compared with clinical parameters where T classification and vocal cord mobility were the only significant parameters associated with local control. Multivariate analysis (Cox regression model) of clinical and radiologic parameters revealed that hypopharyngeal extension (P=.04) and intermediate T2 signal intensity (SI) in cartilage similar to tumor SI (P<.001) were independent prognostic factors with regard to local control. CONCLUSION Intermediate T2 SI in cartilage, which may suggest cartilage invasion, and hypopharyngeal extension of tumor, predict greater likelihood of local failure, whereas high T2 SI, which may suggest inflammatory tissue in cartilage, predicts lower likelihood of local failure.