Subgroup and Prognostic Factor Analysis in T4 Lung Cancer Based on the 9th Tumour-Node-Metastasis Classification.

OBJECTIVES: T4 non-small-cell lung cancer comprises a biologically and anatomically heterogeneous group. The 9th edition of the Tumour-Node-Metastasis staging system introduced refined T4 definitions and subdivided N2 disease into single- and multi-station involvement. This study aimed to assess long-term survival and prognostic factors in surgically treated T4 non-small-cell lung cancer patients, focusing on T4 subgroups and nodal status. METHODS: We retrospectively analysed patients who underwent resection for pathologically confirmed T4 non-small cell lung cancer between 2006 and 2024. Patients were categorized based on T4 criteria: tumour diameter >7 cm, adjacent structure invasion, or multiple T4 features. Survival outcomes were assessed using Kaplan-Meier, Aalen-Johansen and Cox regression analyses. RESULTS: A total of 191 patients were analysed. The 5-year overall survival rate was 34.1%, varying across subgroups: 38.7% (size), 29.9% (invasion), and 6.1% (multiple criteria) (P < .001). Adjuvant chemotherapy was associated with improved overall survival (hazard ratio [HR]: 0.511; P = .001), while N2 disease (HR: 1.750; P = .012) and multiple T4 features (HR: 2.590; P < .001) predicted worse outcomes. Similar patterns were observed in recurrence-free survival. N2 involvement was particularly adverse in the invasion group. CONCLUSIONS: T4 aetiology and nodal status significantly impact survival following surgery. These findings support the prognostic utility of the 9th Tumour-Node-Metastasis edition and underscore the value of tailored surgical strategies.