The TNM 8 M1b and M1c classification for non-small cell lung cancer in a cohort of patients with brain metastases

Abstract

Background and purpose: According to the recent TNM 8 classification, patients with metastatic non-small cell lung cancer (NSCLC) and single extrathoracic metastasis should be classified as stage M1b, while those with 2 or more metastases comprise stage M1c. The purpose of this study was to analyze the impact of this classification in patients with brain metastases.

Materials and methods: This retrospective study included 172 patients treated with individualized approaches. Actuarial survival was calculated. Uni- and multivariate analyses were performed.

Results: Thirty patients (17%) were staged as M1b. Those with squamous cell cancer were more likely to harbor M1b disease (29%, adenocarcinoma 14%, other histology 17%, p = 0.16). Median survival was 5.4 months (8.0 months in case of M1b disease and 4.5 months in case of M1c disease, p = 0.001). Multivariate analysis confirmed the role of M1b stage. M1b patients managed with upfront surgery or radiosurgery had significantly longer median survival than those who received whole-brain irradiation (21.0 vs. 3.5 months, p = 0.0001) and the potential to survive beyond 5 years.

Conclusions: We found the M1b classification to provide clinically relevant information. The multivariate analysis suggested that patients with M1b disease, better performance status and younger age have better survival.

Keywords: Brain metastases; Lung cancer; Prognostic factors; Radiotherapy.