A Comprehensive Review Of Cigarette Smoking And Cancer Treatment: A World Health Organization Tobacco Use Knowledge Summary

Kayo TOGAWA, International Agency for Research on Cancer, France

1 Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France
2 Cluster for Noncommunicable Diseases and Mental Health, World Health Organization, Geneva, Switzerland

Purpose: This WHO Tobacco Knowledge Summary aims to qualitatively summarize the evidence for the adverse effects of post-diagnosis smoking on cancer treatment and its outcomes.  The resulting summary will serve as a tool to involve healthcare providers in the fight against smoking in the cancer population.
Methods: We searched for systematic and comprehensive reviews regarding the effects of post-diagnosis smoking on cancer treatment and its outcomes in three databases, PubMed, Web of Science, and Cochrane Library.  Inclusion and exclusion criteria were then used to select the articles for review.
Results: Out of 1,020 identified articles, 14 review articles were selected for appraisal.  The preliminary review showed evidence of the adverse impact of post-diagnosis smoking on treatment outcomes including progression, recurrence, and survival.  The evidence of adverse impact was strong for lung and head and neck cancers, and to a lesser degree, bladder and breast cancers.  Data were scarce for non-tobacco-related cancers.  The adverse clinical outcomes among patients who continue to smoke after diagnosis can be explained by increased treatment-related complications, altered drug metabolism, or nicotine-induced cell proliferation and inhibition of cell apoptosis, all of which can lead to reduced efficacy of systemic therapy and radiotherapy.
Conclusions: This preliminary review revealed evidence that continued smoking after a cancer diagnosis has negative impacts on cancer treatment and its outcomes, suggesting the need for effective smoking cessation interventions during the course of cancer treatment.  Current evidence is limited to few specific types of cancer and treatment.  More prospective studies are needed to evaluate both biological and clinical effects of post-diagnosis smoking on different types of treatment and its outcomes, particularly for non-tobacco-related cancers. 
Funding source: This work was supported by the European Commission FP7 Marie Curie Actions – People – Co-funding of regional, national and international programmes.