Comparison of 11 staging classifications in carcinoma of the external auditory canal.

Background and purpose: To compare overall survival (OS) differences across 11 different staging classifications.

Materials and methods: Patient data were retrospectively collected. OS curves were estimated by Kaplan-Meier method. Hazard ratios (HR) were calculated by Cox regression. Concordance between HR of each system was evaluated by C-index. Absolute net reclassification improvement (NRI) was performed.

Results: Thirty-five patients fitted study criteria with median follow-up of 27.3 months. 80% were diagnosed with squamous cell carcinoma. 14.3% had ECOG > 1. Eighteen patients underwent surgery, while 31 patients received radiotherapy. For AJCC 8th edition cutaneous carcinoma of the head and neck, 3-year OS of stage 1-3 and 4 was 26.7% (median OS of 0.8 years) and 64.1% (median OS of 4.3 years) (HR 0.33; 95%CI 0.09-1.2). 3-year OS of T1-3 and T4 in modified Pittsburgh classification were 65% and 55.4% with median OS of not reached and 3.1 years (HR 1.86; 95%CI 0.66-5.23). Regarding Kinney system, patients with stage 1-2 and 3 had 3-year OS of 67.1% and 45.5%, while median OS was 4.7 years and 1 year (HR 1.94; 95%CI 0.75-4.97). C-indices were 0.577, 0.523 and 0.569. NRI comparing Kinney with modified Pittsburgh classifications was 2.86%.

Conclusion: Kinney's may offer improved prognostic accuracy compared to other classifications.