Initiation or cessation: what keeps the prevalence of smoking higher in Quebec than in the rest of Canada?

Routine Clinically Detected Increased ROS1 Transcripts Are Related With ROS1 Expression by Immunohistochemistry and Associated With EGFR Mutations in Lung Adenocarcinoma

Introduction

Translocations of the ROS1 gene were found to drive tumorigenesis in 1% to 2% of lung adenocarcinoma. In clinical practice, ROS1 rearrangements are often screened by immunohistochemistry (IHC) before confirmation with either fluorescence in situ hybridization or molecular techniques. This screening test leads to a non-negligible number of cases that have equivocal or positive ROS1 IHC, without ROS1 translocation.

Methods

In this study, we have analyzed retrospectively 1021 cases of nonsquamous NSCLC having both ROS1 IHC and molecular analysis using next-generation sequencing.

Results

ROS1 IHC was negative in 938 cases (91.9%), equivocal in 65 cases (6.4%), and positive in 18 cases (1.7%). Among these 83 equivocal or positive cases, only two were ROS1 rearranged, leading to a low predictive positive value of the IHC test (2%). ROS1-positive IHC was correlated with an increased mRNA ROS1 transcripts. Moreover, we have found a mean statistically significant relationship between ROS1 expression and EGFR gene mutations, suggesting a crosstalk mechanism between these oncogenic driver molecules.

Conclusion

This study demonstrates that ROS1 IHC represents true ROS1 mRNA expression, and raises the question of a potential benefit of combined targeted therapy in EGFR-mutated NSCLC.

Next-generation sequencing of non-small cell lung cancer at a Quebec health care cancer centre

BACKGROUND

Lung cancer is the leading cause of cancer death in both men and women. Quebec has the highest lung cancer mortality out of all provinces in Canada, believed to be caused by higher smoking rates. Molecular testing for lung cancer is standard of care due to the discovery of actionable driver mutations that can be targeted with tyrosine kinase inhibitors. To date, no detailed molecular testing characterization of Quebec patients with lung cancer using next generation sequencing (NGS) has been performed.

MATERIALS AND METHODS

The aim of this study was to describe the genomic landscape of patients with lung cancer (n = 997) who underwent NGS molecular testing at a tertiary care center in Quebec and to correlate it with clinical and pathology variables.

RESULTS

Compared to 10 other NGS studies found through a structured search strategy, our cohort had a higher prevalence of KRAS mutations (39.2%) compared to most geographical locations. Additionally, we observed a significant positive association between decreasing age and a higher proportion of KRAS G12C mutations.

CONCLUSION

Overall, it remains important to assess institutional rates of actionable driver mutations to help guide governing bodies, fuel clinical trials and create benchmarks for expected rates as quality metrics.

Do demographic and socioeconomic characteristics underpin differences in youth smoking initiation across Canadian provinces? Evidence from the Canadian Community Health Survey (2015-2018)

INTRODUCTION

Youth initiation may drive differences in smoking prevalence across Canadian provinces. Provincial differences in initiation relate to tobacco control strategies and public health funding, but have also been attributed to population characteristics. We test this hypothesis by examining the extent to which seven characteristics-immigration, language, family structure, education, income, home ownership and at-school status-explain differences in initiation across provinces.

METHODS

We used data from 16 897 youth aged 12 to 17 years in the Canadian Community Health Survey collected from 2015 to 2018. To examine the proportion of provincial differences explained by population characteristics, we compared average marginal effects (AMEs) from partially and fully adjusted models regressing "having ever initiated" on province and other characteristics. We also tested interactions to examine differences in the association between population characteristics and initiation across provinces.

RESULTS

Initiation varied from 4% in British Columbia to 10% in Quebec. Being born in Canada, speaking French, not living in a two-parent household, being in the lowest household income quintile, having parents without postsecondary education, living in rented accommodation and not being in school were each associated with initiation. Taking these results into consideration, the AME of residing in another province compared with Quebec was attenuated by between 3% and 9%. Family structure and household income were more strongly associated with initiation in the Atlantic region and Manitoba, but not in Quebec.

CONCLUSION

Differences in initiation between Quebec and other provinces are unlikely to be substantially explained by their demographic or socioeconomic composition. Reprioritizing tobacco control and public health funding are likely key in attaining the "tobacco endgame" across provinces.