Risk prediction models for lung cancer in people who have never smoked: a protocol of a systematic review

BACKGROUND

Lung cancer is one of the most commonly diagnosed cancers and the leading cause of cancer-related death worldwide. Although smoking is the primary cause of the cancer, lung cancer is also commonly diagnosed in people who have never smoked. Currently, the proportion of people who have never smoked diagnosed with lung cancer is increasing. Despite this alarming trend, this population is ineligible for lung screening. With the increasing proportion of people who have never smoked among lung cancer cases, there is a pressing need to develop prediction models to identify high-risk people who have never smoked and include them in lung cancer screening programs. Thus, our systematic review is intended to provide a comprehensive summary of the evidence on existing risk prediction models for lung cancer in people who have never smoked.

METHODS

Electronic searches will be conducted in MEDLINE (Ovid), Embase (Ovid), Web of Science Core Collection (Clarivate Analytics), Scopus, and Europe PMC and Open-Access Theses and Dissertations databases. Two reviewers will independently perform title and abstract screening, full-text review, and data extraction using the Covidence review platform. Data extraction will be performed based on the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies (CHARMS). The risk of bias will be evaluated independently by two reviewers using the Prediction model Risk-of-Bias Assessment Tool (PROBAST) tool. If a sufficient number of studies are identified to have externally validated the same prediction model, we will combine model performance measures to evaluate the model's average predictive accuracy (e.g., calibration, discrimination) across diverse settings and populations and explore sources of heterogeneity.

DISCUSSION

The results of the review will identify risk prediction models for lung cancer in people who have never smoked. These will be useful for researchers planning to develop novel prediction models, and for clinical practitioners and policy makers seeking guidance for clinical decision-making and the formulation of future lung cancer screening strategies for people who have never smoked.

SYSTEMATIC REVIEW REGISTRATION

This protocol has been registered in PROSPERO under the registration number CRD42023483824.

Low-Dose Computed Tomography Screening in Relatives With a Family History of Lung Cancer

INTRODUCTION

The role of a family history of lung cancer (LCFH) in screening using low-dose computed tomography (LDCT) has not been prospectively investigated with long-term follow-up.

METHODS

A multicenter prospective study with up to three rounds of annual LDCT screening was conducted to determine the detection rate of lung cancer (LC) in asymptomatic first- or second-degree relatives of LCFH.

RESULTS

From 2007 to 2011, there were 1102 participants enrolled, including 805 and 297 from simplex and multiplex families (MFs), respectively (54.2% women and 70.0% never-smokers). The last follow-up date was May 5, 2021. The overall LC detection rate was 4.5% (50 of 1102). The detection rate in MF was 9.4% (19 of 202) and 4.4% (4 of 91) in never-smokers and in those who smoked, respectively. The corresponding rates for simplex families were 3.7% (21 of 569) and 2.7% (6 of 223), respectively. Of these, 68.0% and 22.0% of cases with stage I and IV diseases, respectively. LC diagnoses within a 3-year interval from the initial screening tend to be younger, have a higher detection rate, and have stage I disease; thereafter, more stage III-IV disease and 66.7% (16 of 24) with negative or semipositive nodules in initial computed tomography scans. Within the 6-year interval, only maternal (modified rate ratio = 4.46, 95% confidence interval: 2.32-8.56) or maternal relative history of LC (modified rate ratio = 5.41, 95% confidence interval: 2.84-10.30) increased the risk of LC.

CONCLUSIONS

LCFH is a risk factor for LC and is increased with MF history, among never-smokers, younger adults, and those with maternal relatives with LC. Randomized controlled trials are needed to confirm the mortality benefit of LDCT screening in those with LCFH.

New insights into the biology and development of lung cancer in never smokers-implications for early detection and treatment

Lung cancer is the leading cause of cancer deaths worldwide. Despite never smokers comprising between 10 and 25% of all cases, lung cancer in never smokers (LCNS) is relatively under characterized from an etiological and biological perspective. The application of multi-omics techniques on large patient cohorts has significantly advanced the current understanding of LCNS tumor biology. By synthesizing the findings of multi-omics studies on LCNS from a clinical perspective, we can directly translate knowledge regarding tumor biology into implications for patient care. Primarily focused on never smokers with lung adenocarcinoma, this review details the predominance of driver mutations, particularly in East Asian patients, as well as the frequency and importance of germline variants in LCNS. The mutational patterns present in LCNS tumors are thoroughly explored, highlighting the high abundance of the APOBEC signature. Moreover, this review recognizes the spectrum of immune profiles present in LCNS tumors and posits how it can be translated to treatment selection. The recurring and novel insights from multi-omics studies on LCNS tumor biology have a wide range of clinical implications. Risk factors such as exposure to outdoor air pollution, second hand smoke, and potentially diet have a genomic imprint in LCNS at varying degrees, and although they do not encompass all LCNS cases, they can be leveraged to stratify risk. Germline variants similarly contribute to a notable proportion of LCNS, which warrants detailed documentation of family history of lung cancer among never smokers and demonstrates value in developing testing for pathogenic variants in never smokers for early detection in the future. Molecular driver subtypes and specific co-mutations and mutational signatures have prognostic value in LCNS and can guide treatment selection. LCNS tumors with no known driver alterations tend to be stem-like and genes contributing to this state may serve as potential therapeutic targets. Overall, the comprehensive findings of multi-omics studies exert a wide influence on clinical management and future research directions in the realm of LCNS.

Smokers have increased risk of soft-tissue complications following primary elective TKA

INTRODUCTION

Smoking has been associated with numerous adverse outcomes following surgical procedures. The purpose of this study was to investigate, whether smoking status at time of surgery influences the outcome of primary TKA.

MATERIALS AND METHODS

Six hundred and eighty-one patients who underwent primary TKA between 2003 and 2006 were included in the study. Smoking status was defined as current, former, and never smoker. Complications leading to revisions were assessed until 17 years of follow-up. Functional outcome was evaluated using clinical scores: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analogue Scale (VAS) for pain, Short Form-12 Physical and Mental Component Summaries (SF-12PCS/MCS), and Knee Society Function and Knee Score (KSFS and KSKS).

RESULTS

At a mean follow-up of 95 months (± 47 months), 124 complications led to revision surgery. Soft-tissue complications (OR, 2.35 [95% CI 1.08-5.11]; p = 0.032), hematoma formation (OR, 5.37 [95% CI 1.01-28.49]; p = 0.048), and restricted movement (OR, 3.51 [95% CI 1.25-9.84]; p = 0.017) were more likely to occur in current smokers than never smokers. Current smokers were more likely to score higher at KSFS (p < 0.001) and SF-12PCS (p = 0.0197) compared to never smokers. For overall revision, differences were noted.

CONCLUSION

Current smoking increases risk of soft-tissue complications and revision after primary TKA, especially due to hematoma and restricted movement. Smoking cessation programs could reduce the risk of revision surgery.

Lung cancer in never smokers: Distinct population-based patterns by age, sex, and race/ethnicity

OBJECTIVES

Epidemiological patterns for lung cancer among never smokers (LCNS) are largely unknown, even though LCNS cases comprise 15% of lung cancers. Past studies were based on epidemiologic or health system cohorts, and not fully representative of the underlying population. The objective was to analyze rates (and trends) of LCNS by sex, age group, and race and ethnicity based on all-inclusive truly population-based sources.

MATERIALS AND METHODS

Individual-level data from 2014 to 2018 on smoking status among microscopically-confirmed lung cancer cases from Florida's cancer registry were combined with population denominators adjusted with NHIS data on smoking prevalence to compute population-based LCNS incidence rates and rate ratios. Incidence rates and proportional mortality were ranked against other cancers. Joinpoint regression analyses examined trends.

RESULTS

Proportions of LCNS ranged from 9% among White men to 83% among Chinese women. Overall, LCNS was 13% (IRR 1.13, 95%CI 1.08-1.17) more common among men than women, but variation occurred by age group, with female rates exceeding male in younger ages. Age-adjusted rates per 100,000 were highest among Asian/Pacific Islander (API) men and women (15.3 and 13.5, respectively) and Black populations (14.6, 12.9), intermediate for White (13.2, 11.8) and lowest among the Hispanic population (12.1, 10.6). Among API women, LCNS was the second leading cause of cancer death, surpassed only by breast cancer. LCNS trends were stable over time.

CONCLUSION

LCNS is the 11th most frequently occurring cancer in men and 8th in women. LCNS differences by race/ethnicity are small, within a 15% range of the White population's rates. Surprisingly, API men and women have the highest LCNS rates and proportional mortality. As smoking prevalence decreases in the US, LCNS cases will inevitably increase, warranting inquiry into risk factors across the lifespan.

Risk factors for the development of lung cancer among never smokers: A systematic review

This review aimed to summarize the up-to-date evidence on non-genetic factors for the development of never smoking lung cancer (NSLC) and to explore reasons behind the conflicting results. Relevant literature was searched in three electronic databases (PubMed, Embase and Web of Science) from 1 January 2000-31 July 2022. Cohort studies that investigated non-genetic risk factors for primary lung cancer in never smokers were included. The effect of non-genetic factors about NSLC were summarized with pooled relative risk (RR) and 95 % confidence intervals (CIs) through meta-analysis or narrative description when unexplained statistical heterogeneity was observed. The Newcastle-Ottawa Scale was used to appraise the methodological quality of included studies. Sixty cohort studies were included, covering population from Asia, Europe and America. Most included studies (42, 70.0 %) were of high methodological quality. Over 50 years old (RR = 5.26), environmental tobacco smoke (Pooled RR = 1.30), Chronic obstructive pulmonary disease (COPD) (RR = 2.67), family history of lung cancer (Pooled RR = 1.83) and higher level of neutrophil-lymphocyte ratio (RR = 1.73) increased the risk of NSLC. Dairy foods consumption (RR = 0.79), isoflavone intake (Pooled RR = 0.65), and riboflavin intake (RR = 0.62) decreased the risk among female population. Inconsistency or unclear definition for never smokers and risk factors could be observed in included studies. Most life behavior factors associated with NSLC can be modified through lifestyle changes. Future cohort studies are suggested to adopt a clearer definition on never smokers and exposure, conducting subgroup analysis when evidence indicating there is heterogeneity between genders, and explore dose-response relationship between the identified factors and NSLC.

Short- and long-term survival outcomes among never smokers who developed lung cancer

BACKGROUND

Lung cancer is the leading cause of cancer death in the US. While an extensive literature exists detailing lung cancer risk factors and mortality among patients with a history of tobacco use, the data are more limited among individuals who have never smoked. The purpose of this investigation is to compare survival rates between the two groups and evaluate potential risk factors among never smokers.

METHODS

This retrospective study included 3380 smokers and 334 never smokers who were diagnosed with lung cancer at Stony Brook University Hospital between 2003 and 2016. 1-, 3-, 5- and 10-year survival outcomes, stratified by smoking status, were compared and Kaplan-Meier curves for overall survival are provided. Cox Proportional Hazard models were used to evaluate factors influencing survival among never smokers.

RESULTS

Never smokers with lung cancer were more likely to be female, be diagnosed with adenocarcinoma histology, and had fewer comorbidities than lung cancer patients who smoked. Although 60% of patients were diagnosed at a later stage of disease development, regardless of smoking status, overall short- and long-term survival was significantly higher among never smokers compared to those with a history of tobacco use. In addition to age and stage at diagnosis, a history of diabetes was found to be a significant prognostic factor for decreased survival among never smokers (HR=3.15, 95% CI (1.74, 5.71)).

CONCLUSIONS

Data from the present investigation suggest that, regardless of smoking status, approximately three of every five lung cancer patients are diagnosed at a later stage, and that both short- and long-term survival outcomes are significantly better among never smokers compared to those with a history of tobacco use. Additional studies are required to validate these findings and better explain the mechanistic drivers for the improved outcomes among never smokers.

High-Ambient Air Pollution Exposure Among Never Smokers Versus Ever Smokers With Lung Cancer

INTRODUCTION

Air pollution may play an important role in the development of lung cancer in people who have never smoked, especially among East Asian women. The aim of this study was to compare cumulative ambient air pollution exposure between ever and never smokers with lung cancer.

METHODS

A consecutive case series of never and ever smokers with newly diagnosed lung cancer were compared regarding their sex, race, and outdoor and household air pollution exposure. Using individual residential history, cumulative exposure to outdoor particulate matter (PM_2.5) in a period of 20 years was quantified with a high-spatial resolution global exposure model.

RESULTS

Of the 1005 patients with lung cancer, 56% were females and 33% were never smokers. Compared with ever smokers with lung cancer, never smokers with lung cancer were significantly younger, more frequently Asian, less likely to have chronic obstructive pulmonary disease or a family history of lung cancer, and had higher exposure to outdoor PM_2.5 but lower exposure to secondhand smoke. Multivariable logistic regression analysis revealed a significant association with never-smoking patients with lung cancer and being female (OR = 4.01, 95% confidence interval [CI]: 2.76-5.82, p < 0.001), being Asian (OR_{Asian versus non-Asian} = 6.48, 95% CI: 4.42-9.50, p < 0.001), and having greater exposure to air pollution (OR_{ln_PM2.5} = 1.79, 95% CI: 1.10-7.2.90, p = 0.019).

CONCLUSIONS

Compared with ever-smoking patients with lung cancer, never-smoking patients had strong associations with being female, being Asian, and having air pollution exposures. Our results suggest that incorporation of cumulative exposure to ambient air pollutants be considered when assessing lung cancer risk in combination with traditional risk factors.

Twenty-year sociodemographic trends in lung cancer in non-smokers: A UK-based cohort study of 3.7 million people

INTRODUCTION

There are reports that lung cancer in non-smokers (LCINS) is increasing in the United Kingdom (UK) and other high-income countries but evidence from large-scale cohort studies to support this claim is limited.

MATERIAL AND METHODS

Using The Health Improvement Network (THIN) IQVIA™ Medical Research Data, we identified a cohort of 3,679,831 people from the UK self-reporting to their primary care physician as never or non-smokers. We estimated age-adjusted incidence rates for recorded lung cancer before (1998-2007) and after (2008-2018) the introduction of smoke-free legislation using multivariable Poisson regression. We also explored the impact of geographic location, social deprivation and urbanicity.

RESULTS

The analysis included 3,212 lung cancer events and 28 million person-years (PYs). Between 1998 and 2007, the age-adjusted rates in men declined by 9% per year (95 %CI: 7-11%) from an estimated 5.6 to 1.5 per 10,000 PYs and by 3% per year (95 %CI: 1-5%) between 2008 and 2018. These trends for men were similar across sociodemographic strata. Between 1998 and 2007, age-adjusted rates were stable for women at 1.5 per 10,000 PYs. However, there was evidence that time trends for women differed depending on levels of social deprivation with rates increasing by 5% per year (95 %CI: 2-9%) from an estimated 1.3-2.1 per 10,000 PYs for women living in the least socially deprived areas. Sex-specific time trends from 2008 to 2016 were broadly similar in a separate cohort of self-reported never smokers from UK Biobank with cancer events linked to national registries.

CONCLUSION

In summary, the incidence of LCINS has reduced or remained stable for most of the UK with the possible exception of women living in the least socially deprived areas.

DNA methylation is associated with lung function in never smokers

BACKGROUND

Active smoking is the main risk factor for COPD. Here, epigenetic mechanisms may play a role, since cigarette smoking is associated with differential DNA methylation in whole blood. So far, it is unclear whether epigenetics also play a role in subjects with COPD who never smoked. Therefore, we aimed to identify differential DNA methylation associated with lung function in never smokers.

METHODS

We determined epigenome-wide DNA methylation levels of 396,243 CpG-sites (Illumina 450 K) in blood of never smokers in four independent cohorts, LifeLines COPD&C (N = 903), LifeLines DEEP (N = 166), Rotterdam Study (RS)-III (N = 150) and RS-BIOS (N = 206). We meta-analyzed the cohort-specific methylation results to identify differentially methylated CpG-sites with FEV₁/FVC. Expression Quantitative Trait Methylation (eQTM) analysis was performed in the Biobank-based Integrative Omics Studies (BIOS).

RESULTS

A total of 36 CpG-sites were associated with FEV₁/FVC in never smokers at p-value< 0.0001, but the meta-analysis did not reveal any epigenome-wide significant CpG-sites. Of interest, 35 of these 36 CpG-sites have not been associated with lung function before in studies including subjects irrespective of smoking history. Among the top hits were cg10012512, cg02885771, annotated to the gene LTV1 Ribosome Biogenesis factor (LTV1), and cg25105536, annotated to Kelch Like Family Member 32 (KLHL32). Moreover, a total of 11 eQTMS were identified.

CONCLUSIONS

With the identification of 35 CpG-sites that are unique for never smokers, our study shows that DNA methylation is also associated with FEV₁/FVC in subjects that never smoked and therefore not merely related to smoking.

Lung Cancer Risk in Never-Smokers of European Descent is Associated With Genetic Variation in the 5p15.33 TERT-CLPTM1Ll Region

INTRODUCTION

Inherited susceptibility to lung cancer risk in never-smokers is poorly understood. The major reason for this gap in knowledge is that this disease is relatively uncommon (except in Asians), making it difficult to assemble an adequate study sample. In this study we conducted a genome-wide association study on the largest, to date, set of European-descent never-smokers with lung cancer.

METHODS

We conducted a two-phase (discovery and replication) genome-wide association study in never-smokers of European descent. We further augmented the sample by performing a meta-analysis with never-smokers from the recent OncoArray study, which resulted in a total of 3636 cases and 6295 controls. We also compare our findings with those in smokers with lung cancer.

RESULTS

We detected three genome-wide statistically significant single nucleotide polymorphisms rs31490 (odds ratio [OR]: 0.769, 95% confidence interval [CI]: 0.722-0.820; p value 5.31 × 10-16), rs380286 (OR: 0.770, 95% CI: 0.723-0.820; p value 4.32 × 10-16), and rs4975616 (OR: 0.778, 95% CI: 0.730-0.829; p value 1.04 × 10-14). All three mapped to Chromosome 5 CLPTM1L-TERT region, previously shown to be associated with lung cancer risk in smokers and in never-smoker Asian women, and risk of other cancers including breast, ovarian, colorectal, and prostate.

CONCLUSIONS

We found that genetic susceptibility to lung cancer in never-smokers is associated to genetic variants with pan-cancer risk effects. The comparison with smokers shows that top variants previously shown to be associated with lung cancer risk only confer risk in the presence of tobacco exposure, underscoring the importance of gene-environment interactions in the etiology of this disease.

Lung cancer survival among never smokers

Lung cancer incidence among never smokers has increased in recent decades with 10-30% of all lung cancers occurring in never smokers, where exposure to residential radon is the leading cause of this disease. Lung cancer survival is low, ranging from 12% to 16% at 5 years of diagnosis. There is scant evidence to date on survival from this disease in never smokers. We aim to evaluate lung cancer survival in never smokers and ascertain whether there might be differences regarding smokers, through a systematic review applying predefined inclusion and exclusion criteria. 17 Studies were included. Never-smoker lung cancer patients seem to experience longer survival times than do smokers or ex-smokers. Lung cancer in never smokers displays distinctive clinical characteristics, is more frequent among women, is diagnosed at more advanced stages, and the predominant histologic type is adenocarcinoma. Further studies are necessary to ascertain lung cancer survival among never smokers.

Airflow limitation classified with the fixed ratio or the lower limit of normal and cause-specific mortality - A prospective study

BACKGROUND

There is controversy as to whether airflow limitation should be defined as forced expiratory volume in 1 s (FEV₁)/vital capacity (VC) < 0.7 or as FEV₁/VC< the lower limit of normal (LLN). The aim was to examine whether different definitions of airflow limitation differ in predicting mortality.

METHODS

Longitudinal prospective study of a national cohort of Swedish workers (199,408 men; 7988 women), aged 20-64 years with spirometry without bronchodilation at baseline followed from 1979 until death, or censorship at 2010. Airflow limitation (AL) by Global Obstructive Lung Disease criteria, AL_GOLD, was defined as FEV₁/VC < 0.7; AL_LLN as FEV₁/VC < LLN. All all-cause, COPD and cardiovascular disease mortality was analyzed among men and women in relation to AL_GOLD and AL_LLN, adjusted for age and smoking.

RESULTS

Among men, all-cause mortality risks were similar by airflow limitation criteria: AL_GOLD RR = 1.32, 95% CI 1.26-1.38; AL_LLN, RR = 1.37, 95% CI 1.31-1.44. The risk estimates were also similar by airflow limitation definition for cardiovascular mortality and for COPD mortality. Among women, all-cause mortality was also similar by airflow limitation criteria, but significantly higher as compared to men: AL_GOLD RR = 2.10, 95% CI 1.66-2.66; AL_LLN, RR = 2.09, 95% CI 1.66-2.62. Also cardiovascular and COPD mortality by airflow limitation criteria was significantly higher among women as compared to men.

CONCLUSIONS

Defined either as FEV₁/VC < 0.7 or as FEV₁/VC < LLN, airflow limitation predicted excess mortality risk of similar magnitude. Mortality in relation to airflow limitation was higher among women compared to men.

Serum 25-hydroxyvitamin D concentrations and lung cancer risk in never-smoking postmenopausal women

PURPOSE

Vitamin D has been implicated in lowering lung cancer risk, but serological data on the association among never-smoking women are limited. We report results examining the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with lung cancer risk among female never smokers. We also examined whether the association was modified by vitamin D supplementation and serum vitamin A concentrations.

METHODS

In the Women's Health Initiative, including the calcium/vitamin D (CaD) Trial, we selected 298 incident cases [191 non-small cell lung cancer (NSCLC) including 170 adenocarcinoma] and 298 matched controls of never smokers. Baseline serum 25(OH)D was assayed by a chemiluminescent method. Logistic regression was used to estimate odds ratios (ORs) for quartiles and predefined clinical cutoffs of serum 25(OH)D concentrations.

RESULTS

Comparing quartiles 4 versus 1 of serum 25(OH)D concentrations, ORs were 1.06 [95% confidence interval (CI) 0.61-1.84] for all lung cancer, 0.94 (95% CI 0.52-1.69) for NSCLC, and 0.91 (95% CI 0.49-1.68) for adenocarcinoma. Comparing serum 25(OH)D ≥ 75 (high) versus <30 nmol/L (deficient), ORs were 0.76 (95% CI 0.31-1.84) for all lung cancer, 0.71 (95% CI 0.27-1.86) for NSCLC, and 0.81 (95% CI 0.31-2.14) for adenocarcinoma. There is suggestive evidence that CaD supplementation (1 g calcium + 400 IU D₃/day) and a high level of circulating vitamin A may modify the associations of 25(OH)D with lung cancer overall and subtypes (p interaction <0.10).

CONCLUSIONS

In this group of never-smoking postmenopausal women, the results did not support the hypothesis of an association between serum 25(OH)D and lung cancer risk.

Serum cotinine levels and diabetes mellitus in never smokers

OBJECTIVE

The aim of the current study is to examine the association of environmental tobacco smoke (ETS) exposure evident by serum cotinine level, and diabetes mellitus in never smokers. Previous studies suggest that active tobacco cigarette smoking is associated with diabetes mellitus risk. However it is not clear if the low-level "background" ETS exposure is associated with diabetes among never smokers.

METHODS

We present evidence from five independent replications based on the US nationally representative National Health and Nutrition Examination Surveys (NHANES) conducted 2003-12. Our exposure of interest is ETS exposure among never smokers, measured by serum cotinine levels (ng/mL), and our main outcome is diabetes mellitus assessed via self-reported physician-diagnosis, current use of insulin and/or oral hypoglycemic medications, plasma fasting glucose levels ≥126mg/dL or glycohemoglobin levels ≥6.5%. The conceptual model encompassed age, sex, ethnic self-identification, education, poverty-income ratio, alcohol drinking, total cholesterol and body mass index.

RESULTS

In never smokers, higher serum cotinine levels were positively associated with diabetes mellitus (the meta-analytic summary estimate is 1.2, 95% CI=1.1, 1.2). This association was not evident among never smokers with cotinine levels below 3ng/mL.

CONCLUSIONS

These replications help sustain evidence of ETS-diabetes mellitus association, which might be explained by shared psychosocial characteristics. Prospective studies with appropriate biomarkers are needed to further investigate this association.

Prevalence and risk factors of COPD among never-smokers in two areas of Sweden - Occupational exposure to gas, dust or fumes is an important risk factor

BACKGROUND

Although active tobacco smoking is the main risk factor for COPD, COPD is not uncommon also among never-smokers. Different study locations along with different spirometric definitions of COPD have historically yielded different prevalence estimates of the disease.

AIM

To study current prevalence and risk factors of COPD among never-smokers in two areas of Sweden.

METHODS

Data collected in 2008-2012 within the West Sweden Asthma Study and Obstructive Lung Disease in Northern Sweden Studies was pooled. The study population consisted of 1839 subjects who participated in spirometry and interviews. COPD was defined as post-bronchodilator a) FEV(1)/(F)VC < 0.7, b) FEV(1)/FVC < 0.7 and c) FEV(1)/FVC < lower limit of normal.

RESULTS

Of the 1839 subjects, 967 (52.6%) were never-smokers. Among the never-smoking subjects, the prevalence of COPD according to definitions a-c was 7.7%, 4.9% and 3.0%, respectively. The corresponding prevalence of GOLD grade ≥2 was 2.0%, 1.4% and 1.3%. No significant difference in prevalence between the two study areas was observed. In never-smokers, occupational exposure to gas, dust or fumes (GDF) was significantly associated with both COPD (OR 1.85, 95% CI 1.03-3.33), and GOLD ≥2 (OR 4.51, 1.72-11.9) according to definition a), after adjusting for age, educational level and exposure to passive smoking at work.

CONCLUSION

Depending on definition, prevalence of COPD among never-smokers was 3.0-7.7%, whereas GOLD ≥2 was present in 1.3-2.0%. Occupational exposure to GDF remained independently and significantly associated with COPD regardless of spirometric definition of the disease.

Secondhand smoke exposure (SHS) and health-related quality of life (HRQoL) in Chinese never smokers in Hong Kong

OBJECTIVE

The evidence on the effect of secondhand smoke (SHS) on Health Related Quality of Life (HRQoL) is limited. We examined the relation between SHS and HRQoL among Chinese in Hong Kong.

METHODS

Adult never smokers from a probability sample of three cross-sectional waves (2010, 2012, 2013) of The Hong Kong Family and Health Information Trends Survey who completed the Cantonese-version of Short-Form 12 Health Survey Questionnaire (SF12v2) were included in the data analysis conducted in 2014. Models were used to examine associations of SHS with SF12 domains and summary scores of Physical (PCS12) and Mental Component (MCS12) with subgroups analysis by SHS locations.

RESULTS

After adjustments, SHS was associated with lower scores on all SF12 domains except physical functioning. PCS12 (regress coefficient=-0.76, 95% CI -1.34 to -0.17) and MCS12 (regress coefficient=-1.35, 95% CI -2.06 to -0.64) were lower in those with SHS exposure than those non-exposed. Those exposed to SHS in outdoor public places had lower scores on most SF12 domains and PSC12 and MCS12. SHS exposure in one's home and workplace was associated with lower scores on role physical, body pain and role emotional while SHS exposure in friends' homes was additionally associated with lower social functioning and mental health scores. Lower MCS12 was associated with SHS exposure at all locations except one's home.

CONCLUSIONS

Our study showed that SHS exposure, particularly in outdoor public places, was associated with decreased HRQoL. It can provide new evidence for stronger smoke-free policies on public places and promoting smoke-free homes.

A case-control study

We aim to assess the relationship between leisure time activities related to exposure to carcinogenic substances and lung cancer risk in a hospital-based case-control study performed in never smokers. We included never smoking cases with anatomopathologically confirmed lung cancer and never smoking controls undergoing trivial surgery, at 8 Spanish hospitals. The study was conducted between January 2011 and June 2013. Participants were older than 30 and had no previous neoplasms. All were personally interviewed focusing on lifestyle, environmental tobacco smoke exposure, occupational history and leisure time activities (including duration of such activities). Results were analyzed through logistic regression and adjusted also by residential radon and education level. We included 513 never smokers, 191 cases and 322 controls. The OR for those performing the studied leisure time activities was 1.43 (95%CI 0.78-2.61). When we restricted the analysis to those performing do-it-yourself activities for more than 10 years the OR was 2.21 (95%CI 0.93-5.27). Environmental tobacco smoke exposure did not modify this association. The effect for the different lung cancer histological types was very close to significance for adenocarcinoma but only when these activities were performed for more than 10 years. We encourage health professionals to recommend protective measures for those individuals while performing these hobbies to reduce the risk of lung cancer.

Success and failure rates of tumor genotyping techniques in routine pathological samples with non-small-cell lung cancer

INTRODUCTION

Identification of some somatic molecular alterations in non-small-cell lung cancer (NSCLC) has become evidence-based practice. The success and failure rate of using commercially available tumor genotyping techniques in routine day-to-day NSCLC pathology samples is not well described. We sought to evaluate the success and failure rate of EGFR mutation, KRAS mutation, and ALK FISH in a cohort of lung cancers subjected to routine clinical tumor genotype.

METHODS

Clinicopathologic data, tumor genotype success and failure rates were retrospectively compiled and analyzed from 381 patient-tumor samples.

RESULTS

From these 381 patients with lung cancer, the mean age was 65 years, 61.2% were women, 75.9% were white, 27.8% were never smokers, 73.8% had advanced NSCLC and 86.1% had adenocarcinoma histology. The tumor tissue was obtained from surgical specimens in 48.8%, core needle biopsies in 17.9%, and as cell blocks from aspirates or fluid in 33.3% of cases. Anatomic sites for tissue collection included lung (49.3%), lymph nodes (22.3%), pleura (11.8%), bone (6.0%), brain (6.0%), among others. The overall success rate for EGFR mutation analysis was 94.2%, for KRAS mutation 91.6% and for ALK FISH 91.6%. The highest failure rates were observed when the tissue was obtained from image-guided percutaneous transthoracic core-needle biopsies (31.8%, 27.3%, and 35.3% for EGFR, KRAS, and ALK tests, respectively) and bone specimens (23.1%, 15.4%, and 23.1%, respectively). In specimens obtained from bone, the failure rates were significantly higher for biopsies than resection specimens (40% vs. 0%, p=0.024 for EGFR) and for decalcified compared to non-decalcified samples (60% vs. 5.5%, p=0.021 for EGFR).

CONCLUSIONS

Tumor genotype techniques are feasible in most samples, outside small image-guided percutaneous transthoracic core-needle biopsies and bone samples from core biopsies with decalcification, and therefore expansion of routine tumor genotype into the care of patients with NSCLC may not require special tissue acquisition or manipulation.

A systematic review

Radon exposure is considered the second cause of lung cancer and the first in never smokers. We aim to assess the effect of residential radon exposure on the risk of lung cancer in never smokers through a systematic review applying predefined inclusion and exclusion criteria. 14 Studies were included. Some of them point to a relationship between residential radon and lung cancer while others show no association. Further studies are necessary to test this association and to assess if other risk factors such as environmental tobacco smoke could modify the effect of residential radon exposure on lung cancer.

Smoking status and self-reported race affect the frequency of clinically relevant oncogenic alterations in non-small-cell lung cancers at a United States-based academic medical practice

INTRODUCTION

The identification of somatic genomic aberrations in non-small-cell lung cancer (NSCLC) is part of evidence-based practice guidelines for care of patients with NSCLC. We sought to establish the frequency and correlates with these changes in routine patient-tumor sample pairs.

METHODS

Clinicopathologic data and tumor genotype were retrospectively compiled and analyzed from an overall cohort of 381 patient-tumor samples.

RESULTS

Of these patients, 75.9% self-reported White race, 13.1% Asian, 6.5% Black, 27.8% were never-smokers, 54.9% former-smokers and 17.3% current-smokers. The frequency of EGFR mutations was 23.9% (86/359), KRAS mutations 34.2% (71/207) and ALK FISH positivity 9.1% (23/252) in tumor samples, and almost all had mutually exclusive results for these oncogenes. In tumors from White, Black and Asian patients, the frequencies of EGFR mutations were 18.4%, 18.2% and 62%, respectively; of ALK FISH positivity 7.81%, 0% and 14.8%, respectively; and of KRAS mutations 41.6%, 20% and 0%. These patterns changed significant with increasing pack-year history of smoking. In White patients, the frequencies of EGFR mutations and ALK FISH positivity decreased with increasing pack-year cohorts; while the frequencies of KRAS mutations increased. Interestingly, in Asian patients the frequencies of EGFR mutations were similar in never smokers and in the cohorts with less than 45pack-year histories of smoking and only decreased in the 45pack-year plus cohort.

CONCLUSIONS

The frequencies of somatic EGFR, KRAS, and ALK gene abnormalities using routine lung cancer tissue samples from our United States-based academic medical practice reflect the diverse ethnicity (with a higher frequency of EGFR mutations in Asian patients) and smoking patterns (with an inverse correlation between EGFR mutation and ALK rearrangement) of our tested population. These results may help other medical practices appreciate the expected results from introduction of routine tumor genotyping techniques into their day-to-day care of NSCLC.

Lung cancer in never smokers: disease characteristics and risk factors

It is estimated that approximately 25% of all lung cancer cases are observed in never-smokers and its incidence is expected to increase due to smoking prevention programs. Risk factors for the development of lung cancer described include second-hand smoking, radon exposure, occupational exposure to carcinogens and to cooking oil fumes and indoor coal burning. Other factors reported are infections (HPV and Mycobacterium tuberculosis), hormonal and diatery factors and diabetes mellitus. Having an affected relative also increases the risk for lung cancer while recent studies have identified several single nucleotide polymorphisms associated with increased risk for lung cancer development in never smokers. Distinct clinical, pathology and molecular characteristics are observed in lung cancer in never smokers; more frequently is observed in females and adenocarcinoma is the predominant histology while it has a different pattern of molecular alterations. The purpose of this review is to summarize our current knowledge of this disease.