Investigation of the non-size determined T4N0-2M0 non-small cell lung cancer: what is the proper T category for the tumor with additional nodules in different lobes of ipsilateral lung?

Abstract

This study aimed to explore the prognostic disparity among T4N0-2M0 non-small cell lung cancer patients with different T4 descriptors. T3-4N0-2M0 non-small cell lung cancer patients were included. Patients were assigned to seven subgroups: T3, T4 tumors with size larger than 70 mm (T4-size), T4 tumors with aorta/vena cava/heart invasion (T4-blood vessels), T4 tumors with vertebra invasion (T4-vertebra), T4 tumors with carina/trachea invasion (T4-carina/trachea); T4 tumors with additional tumor nodules in different lobes of ipsilateral lung (T4-add) and T4 tumors had at least two T4 descriptors (T4-multiple). Univariable and multivariable Cox analyses were used to explore the effect of T4 category on overall survival. Kaplan-Meier method with log-rank test was used to compare survival differences among subgroups. Propensity score matching was used to minimize the bias caused by imbalanced covariates between groups. A total of 41,303 eligible T3-4N0-2M0 non-small cell lung cancer cases were included (17,057 T3 cases and 24,246 T4 cases). There were 10,682 cases, 573 cases, 557 cases, 64 cases, 2,888 cases and 9,482 cases in the T4-size, T4-blood vessels, T4-vertebra, T4-carina/trachea, T4-add and T4-multiple subgroups, respectively. Multivariable Cox analyses revealed that T4-add patients had the best prognosis in the entire cohort and in several subgroups. In the matched cohort of T4-add & T4-size and T4-add & T3, the survival of T4-add patients was superior to that of T4-size patients (P < 0.001), but were comparable to that of T3 patients (P = 0.115). Among non-small cell lung cancer patients with different T4 descriptors, T4-add patients had the best prognosis. T4-add patients and T3 patients had similar survivals. Herein, we proposed that T4-add patients should be downstaged from T4 to T3 category. Our results served as a novel supplement to the proposals for the T category revision.