*4.5. Subgroup Analysis*

At initial presentation, +mETE patients presented significantly more often with lymph node metastases (N1-stage 46% in +mETE patients vs. 29% in −mETE patients) as presented in Table 1. Therefore, we performed a subgroup analysis. We compared patients without local lymph node metastases (N0-stage) or with unknown lymph node status (Nx-stage) to patients with local lymph node metastases in the central (N1a-stage) or the latero-cervical compartment (N1b-stage) to identify possible influence of N-stage regarding response rate.
