Prognostic difference between each T3 descriptor in T3N0-3M0 non-small-cell lung cancer.

Abstract

The American Joint Committee on Cancer tumour-node-metastasis (TNM) staging manual is revised every few years. The current 8th edition of the TNM staging manual was published in 2017 and revised to reflect prognosis of patients with non-small-cell lung cancer (NSCLC) [1]. In particular, the T descriptors have been subdivided based on the largest dimension of the solid component, rather than tumour diameter. This is because tumour size is determined by the largest dimension of the solid component on computed tomography (clinical) or the invasive component (pathological). In the current 8th TNM staging, T3 descriptors include tumours larger than 5 cm but equal to <7 cm in greatest dimension (T-size), chest wall invasion (T-chest; parietal pleural invasion and Pancoast tumours), pericardium invasion (T-pericardium), phrenic nerve invasion (T-phrenic nerve) and additional tumour nodules in the same lobe (T-add). Cai et al. [2] evaluated survival disparities among the T3N0-3M0 NSCLC patients using the Surveillance, Epidemiology, and End Results database. A series of 28 159 eligible cases were included from the Surveillance, Epidemiology, and End Results database between 2004 and 2016. The authors combined T-chest, T-pericardium and T-phrenic nerve into 1 group (T-invasion) due to the small number of cases in the T-pericardium and T-phrenic nerve. T-multiple was defined as the tumours having at least 2 T3 descriptors. As a result, the authors classified the T3 descriptors into 4 groups (T-size, T-invasion, T-add and T-multiple) and compared the prognostic differences. In this study, overall survival and cancer-specific survival were compared using the Kaplan–Meier method with a log-rank test and the prognostic factors of this cohort were determined using univariable and multivariable Cox regression models. The survival data showed that T-add patients had the best survival rates compared to other T3 patients. T-add patients had the best prognosis in both the pathological and clinical TNM stage cohorts, followed by T-size and T-multiple patients, and T-multiple patients had the worst prognosis. Multivariable Cox models indicated that T3 descriptors were an important prognostic factor. They concluded that the survival differences exist among the T3N0-3M0 NSCLC patients with different T3 descriptors and this should be taken into account in the next version of the TNM staging manual.