Figure3 Multivariate regression analysis of factors influencing overall survival.
Cause of death
Fifty-one patients died as of the last follow-up date. The main causes of death included systemic distant metastasis (18 cases, 35.3%), including lung metastasis (9 cases), liver metastasis (5 cases), bone metastasis (3 cases) and brain metastasis (1 case); second primary cancer (11 cases, 21.6%), including middle and lower oesophageal cancers (7 cases), central lung cancer (3 cases) and gastric cancer (1 case) and nontumour causes of death (9 cases, 17.6%), including respiratory failure (3 cases) and cardiogenic death (2 cases), severe pneumonia (1 case), asphyxia caused by sputum thrombus (1 case) and unknown causes (2 cases). Local metastases of cervical lymph nodes were found in 7 cases (13.7%). Local tumour recurrence was found in 6 cases (11.8%).