The prognostic impact of the smoking status of cancer patients receiving systemic treatment, radiation therapy, and surgery: A systematic review and meta-analysis

INTRODUCTION: Cigarette smoking represents the main risk factor for cancer development; however, less is known about the effects of active smoking on the outcome of cancer patients receiving systemic treatment, radiation therapy, or surgery.

METHODS: A systematic review and meta-analysis were conducted searching the PubMed® and Web of Science® Library databases using specific Medical Subject Headings terms. Studies reporting on the prognostic impact of the smoking status concerning survival endpoints in cancer patients treated with systemic treatment, radiation therapy, or surgery were eligible for inclusion.

RESULTS: Of 1.380 articles reviewed, 12 reports including data from 31.785 patients with six different cancer types were considered eligible for inclusion. According to the meta-analysis of the overall effect, active smoking during cancer treatment was associated with an impaired overall survival (OS) and cancer-specific mortality (CSM) as compared to former or never smokers (OS: hazard ratio (HR) = 1.61, 95% CI: 1.19-2.17, p = 0.007; CSM: HR = 1.25, 95% CI: 1.01-1.54, p = 0.046). Moreover, smoking cessation led to a similar OS and CSM when comparing former to never smoking patients (OS: HR = 1.01, 95% CI: 0.87-1.18, p = 0.818; CSM: HR = 1.04, 95% CI: 0.91-1.20, p = 0.324).

CONCLUSION: These results underline active smoking during cancer treatment as an independent adverse prognostic factor, while smoking cessation can result in similar outcomes compared to never smokers. Limitations of the study were a substantial study heterogeneity concerning different cancer entities and variations of treatment modalities.