Subgroup and prognostic factor analysis in T4 lung cancer based on the 9th Tumor-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 analyzed 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 analyzed. The 5-year overall survival rate was 34.1%, varying across subgroups: 38.7% (size), 29.9% (invasion), and 6.1% (multiple criteria) (p < 0.001). Adjuvant chemotherapy was associated with improved overall survival (HR: 0.511; p = 0.001), while N2 disease (HR: 1.750; p = 0.012) and multiple T4 features (HR: 2.590; p < 0.001) 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.