Do the smoking intensity and duration, the years since quitting, the methodological quality and the year of publication of the studies affect the results of the meta-analysis on cigarette smoking and Acute Myeloid Leukemia (AML) in adults?

Background: The aim was to perform a systematic review and meta-analysis on the relationship between tobacco smoking and the onset of acute myeloid leukemia (AML) in adults. Methods: PubMed and Scopus databases were systematically searched. In the meta-analysis, random or fixed effects models were used according to the presence of heterogeneity. Study quality was assessed using the Newcastle-Ottawa Scale. Results: Twenty-seven articles were included. Case-control and cohort meta-analyses show that current, ever and former smokers have a significant increased risk to develop AML compared to never smokers [current: OR = 1.36 (1.11-1.66) and RR = 1.52 (1.10-2.14); ever: OR= 1.25 (1.14-1.38) and RR=1.45 (1.10-1.90); former: OR= 1.21 (1.03-1.41) and RR = 1.45 (1.08-1.94)]. Moreover, increasing smoking intensity and duration is associated with an increase of the risk, OR shift from 1.14 (1-20 pack/years) to 2.36 (>40 pack/years). Discussion and conclusion: Smoking may have a significant role in AML onset in a multistep pathogenesis. (C) 2016 Elsevier Ireland Ltd. All rights reserved.