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

## TL;DR

This study examines survival and prognostic factors in T4 non-small-cell lung cancer patients based on the 9th edition of the Tumour-Node-Metastasis staging system.

## Contribution

The study provides new insights into the prognostic significance of T4 subgroups and nodal status in surgically treated T4 lung cancer patients.

## Key findings

- Patients with T4 lung cancer defined by multiple criteria had the lowest 5-year survival rate (6.1%).
- Adjuvant chemotherapy improved overall survival, while N2 disease and multiple T4 features predicted worse outcomes.
- N2 involvement had a particularly adverse effect on survival in patients with tumour invasion.

## Abstract

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.

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.

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.

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.

Prognostic factors in lung cancer critically influence tumour behaviour, treatment response, and survival.