Impact of smoking on survival in nasopharyngeal carcinoma: A cohort study with 23,325 patients diagnosed from 1990 to 2016

Radiother Oncol. 2021 Sep;162:7-17. doi: 10.1016/j.radonc.2021.06.029. Epub 2021 Jun 25.

Abstract

Background: We aimed to compare the survival outcomes of patients with nasopharyngeal carcinoma (NPC) who had different smoking behaviors and were treated with two- or three-dimensional radiotherapy (2D/3DRT) or intensity-modulated radiotherapy (IMRT) with a long-term follow up.

Methods: From 1990 to 2016, 23,325 patients with NPC were included. The primary endpoint of this study was overall survival (OS). The log-rank test and Cox proportional hazards regression model were used to assess the patients' survival outcomes.

Results: The 5-year OS rates in the entire cohort were 76.4%, 68.9%, and 79.8% in the former, current, and never smokers, respectively. In the IMRT cohort, the OS rates showed the same trend. Compared with the never smokers, the 5-year distant metastasis-free survival (DMFS) was lower in the former (P = 0.004) and current smokers (P < 0.001). In the multivariate analysis of the IMRT cohort, the risk of death (P = 0.003) and recurrence (P = 0.027) was higher in the current smokers, while the risk of metastasis was higher in the former and current smokers (P = 0.031 and P = 0.019, respectively) than the never smokers. A total of 53.9% of the effect of smoking status on OS was through sex, age, and Epstein-Barr virus DNA, which were significant mediators.

Conclusion: In the IMRT era, being a former smoker or current smoker was an independent risk factor for DMFS. The difference in OS and locoregional relapse-free survival was significant only between the current smokers and never smokers.

Keywords: EBV DNA; IMRT; Nasopharyngeal carcinoma; Smoking; Survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma*
  • Cohort Studies
  • DNA, Viral
  • Disease-Free Survival
  • Epstein-Barr Virus Infections*
  • Herpesvirus 4, Human / genetics
  • Humans
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms* / radiotherapy
  • Neoplasm Recurrence, Local
  • Prognosis
  • Radiotherapy, Intensity-Modulated*
  • Retrospective Studies
  • Smoking / adverse effects

Substances

  • DNA, Viral