Reporting of tobacco use and impact on outcomes in cancer cooperative group clinical trials: A systematic scoping review.
Authors: Eng Lawson , Brual Janette , Nagee Ahsas , Mok Spencer , Fazelzad Rouhi , Truscott Rebecca , Mittmann Nicole , Chaiton Michael , Saunders Deborah , Liu Geoffrey , Bradbury Penelope Ann , Evans William K. , Papadakos Janet , Giuliani Meredith Elana 
Published: September 2021

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Background: Continued smoking after a diagnosis of cancer negatively impacts cancer outcomes but the impact of tobacco on many innovative treatments has not yet been well established. Collecting and evaluating tobacco use in cancer clinical trials may advance understanding of the consequences of tobacco use on specific treatment modalities. We performed a systematic scoping review of the frequency of reporting and analysis of tobacco use in clinical trials run by cancer cooperative clinical trial groups. Methods: A comprehensive literature search was conducted to identify cancer cooperative group clinical trials published from January 2017 to October 2019 using Medline, Epub Ahead of Print and In-Process & Other Non-Indexed Citations, Embase, Cochrane Central Register of Controlled Trials using OvidSP. Eligible studies evaluated either systemic and/or radiation therapies, involved at least one cancer cooperative group, included > 100 adult patients and reported on at least one primary or secondary endpoint, which included overall survival (OS), disease/progression-free survival (DFS/PFS), response rates, toxicities/adverse events, or quality of life (QoL). Secondary analyses of previously published trials were excluded. Results: Among 14843 identified studies, 91 studies representing 90 trials met inclusion criteria. 24% were phase II trials, 2% phase II/III and 74% phase III. Trial start dates ranged from 1995-2015 with most (29%) between 2007-2008; median trial sample size was 406 (range: 100-4994); 86% involved systematic therapy, 35% involved radiation; 14% were lung and 5% were head and neck trials. 51% of trials had a curative intent, 33% were palliative and 16% involved hematologic cancers. 74 studies reported on OS, 73 DFS/PFS, and 88 toxicity/QoL. 19 studies reported baseline tobacco use information, while two reported collecting follow-up tobacco use. Of those collecting baseline tobacco use, only 7 reported any analysis of the impact of tobacco on clinical outcomes. There was significant heterogeneity in the reporting of baseline tobacco use: 5 reported never/ever status, 10 reported never/ex-smoker/current smoker status; 4 reported some measure of smoking intensity; none reported on verifying smoking status or second hand smoke exposure. Trials of tobacco related (lung and head and neck) cancers were more likely to report baseline tobacco use compared to non-tobacco related cancers (83% vs 6% p < 0.001). Conclusions: Few cancer cooperative group clinical trials report and analyze trial participants’ baseline tobacco use, and even fewer collect follow up information. Significant heterogeneity exists in reporting tobacco use. Routine standardized collection and reporting of tobacco use, both at baseline and follow up in clinical trials, should be implemented to enable investigators to evaluate the clinical impact of tobacco use on new cancer therapies.