Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2020 Aug 28;15(8):e0237723. doi: 10.1371/journal.pone.0237723

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2020 Thomas et al

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

PMC Copyright notice

Fig 1 — Recruitment phase: A total of 4957 subjects were recruited which consisted of 3534 Upper aerodigestive tract (UADT) cancer cases and 1423 healthy controls. It included 1614 lung cancer cases and 1920 Head and Neck cancer (HNC) cases. Inclusion/Exclusion phase: Only current and former smokers were used in the study analysis. A total of 1153 lung cancer cases, 1382 HNC cases, and 643 controls met these criteria. Subjects who missed all FTND variables were excluded from the analysis. Analytic phase: 1130 lung cancer cases, 1230 HNC cases, and 604 controls were included in the statistical analysis. TSSS = time since stopped smoking; FTND = Fagerström Test for Nicotine Dependence.