A Proposal to Modify the 8th IASLC System: Is it Suitable for T4N2M0 Lung Adenocarcinoma to Be Placed in Stage IIIB?

The International Association for the Study of Lung Cancer (IASLC) of TNM staging system has been well accepted as a precise model. However, the latest American Joint Committee on Cancer (AJCC) staging system to solve the different survival and prognosis of lung adenocarcinoma in the same period is still controversial. Therefore, it is necessary to thoroughly explore the applicability between the new system and survival prediction in terms of lung adenocarcinoma. METHODS: We recruited 52,517 patients with lung adenocarcinoma from the Surveillence, Epidemiology, and End Results database. Cox regression analysis was performed to determine survival related factors. The mortality rate per 1000 persons per year of the T4N2M0 lung adenocarcinoma stage and other stages were compared. Survival curves were obtained using the Kaplan-Meier analysis and log-rank test. RESULTS: The results of Cox proportional hazards regression analysis showed that age at diagnosis, race, T stage, distant metastasis, extrathoracic extension, radiotherapy, chemotherapy, and surgery are independent factors related to cancer-specific survival (CSS) and all-cause survival. Furthermore, patients with stage IIIA disease (P<0.001) and IIIB disease (P<0.001) excluding stage at T4N2M0 had a significantly lower risk of CSS and all-cause survival than those staged with T4N2M0 disease. The mortality rates per 1000 person-years with patients staged at T4N2M0 lung adenocarcinoma had higher mortality than patients in the same period. The CSS curves of patients with stage T4N2M0 reflected an obvious decline compared with those of stages IIIA disease and IIIB excluding T4N2M0, and there is no significant difference between this curve and stage IIIC patients (P>0.05). CONCLUSION: The survival rate of patients with T4N2M0 stage was significantly lower than that of patients with IIIA and IIIB stages excluding T4N2M0, there was no significant difference between T4N2M0 and IIIC. It was suggested that this group of patients with stage T4N2M0 were upgraded in the 8th IASLC system.