***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: The contribution of emphysema to lung cancer risk has been recognized , but the effect size needs to be further defined . In this study , 565 primary lung cancer cases were enrolled though a prospect i ve lung cancer cohort at Mayo Clinic , and 450 controls were smokers participating in a lung cancer screening study in the same institution using spiral computed tomography ( CT ) .  Cases and controls were frequency matched on age , gender , race , smoking status , and residential region . CT imaging using st and ard protocol at the time of lung cancer diagnosis ( case ) or during the study ( control ) was assessed for emphysema by visual scoring CT analysis as a percentage of lung tissue destroyed . The clinical definition of emphysema was the diagnosis recorded in the medical documentation . Using multiple logistic regression models , emphysema ( ≥5 % on CT ) was found to be associated with a 3.8-fold increased  lung cancer risk in Caucasians , with higher risk in subgroups of younger ( < 65 years old , OR = 4.64 ) , heavy smokers ( ≥40 pack-years , OR = 4.46 ) , and small-cell lung cancer ( OR = 5.62 ) . When using > 0 % or ≥10 % emphysema on CT , lung cancer risk was 2.79-fold or 3.33-fold higher than controls . Compared with CT evaluation ( using criterion ≥5 % ) , the sensitivity , specificity , positive and negative predictive values , and the accuracy of the clinical diagnosis for emphysema in controls were 19 % , 98 % , 73 % , 84 % , and 83 % , respectively . These results imply that an accurate evaluation of emphysema could help reliably identify individuals at greater risk of lung cancer among smokers . Cancer Prev Res ; 4(1 ) ; 43–50 . © 2010 AACR Prolonged cigarette smoking causes even more deaths from other diseases than from lung cancer . In developed countries , the absolute age-sex-specific lung cancer rates can be used to indicate the approximate proportions due to tobacco of deaths not only from lung cancer itself but also , indirectly , from vascular disease and from various other categories of disease . Even in the absence of direct information on smoking histories , therefore , national mortality from tobacco can be estimated approximately just from the disease mortality statistics that are available from all major developed countries for about 1985 ( and for 1975 and so , by extrapolation , for 1995 ) . The relation between the absolute excess of lung cancer and the proportional excess of other diseases can only be approximate , and so as not to overestimate the effects of tobacco it has been taken to be only half that suggested by a recent large prospect i ve study of smoking and death among one million Americans . Application of such methods indicates that , in developed countries alone , annual deaths from smoking number about 0.9 million in 1965 , 1.3 million in 1975 , 1.7 million in 1985 , and 2.1 million in 1995 ( and hence about 21 million in the decade 1990 - 99 : 5 - 6 million European Community , 5 - 6 million USA , 5 million former USSR , 3 million Eastern and other Europe , and 2 million elsewhere , [ ie , Australia , Canada , Japan , and New Zeal and ] ) . More than half these deaths will be at 35 - 69 years of age : during the 1990s tobacco will in developed countries cause about 30 % of all deaths at 35 - 69 ( making it the largest single cause of premature death ) plus about 14 % of all at older ages . Those killed at older ages are on average already almost 80 years old , however , and might have died soon anyway , but those killed by tobacco at 35 - 69 lose an average of about 23 years of life . At present just under 20 % of all deaths in developed countries are attributed to tobacco , but this percentage is still rising , suggesting that on current smoking patterns just over 20 % of those now living in developed countries will eventually be killed by tobacco ( ie , about a quarter of a billion , out of a current total population of just under one and a quarter billion ) Chronic obstructive pulmonary disease ( COPD ) is a common comorbid disease in lung cancer , estimated to affect 40–70 % of lung cancer patients , depending on diagnostic criteria . As smoking exposure is found in 85–90 % of those diagnosed with either COPD or lung cancer , coexisting disease could merely reflect a shared smoking exposure . Potential confounding by age , sex and pack-yr smoking history , and /or by the possible effects of lung cancer on spirometry , may result in over-diagnosis of COPD prevalence . In the present study , the prevalence of COPD ( pre-bronchodilator Global Initiative for Chronic Obstructive Lung Disease 2 + criteria ) in patients diagnosed with lung cancer was 50 % compared with 8 % in a r and omly recruited community control group , matched for age , sex and pack-yr smoking exposure ( n = 602 , odds ratio 11.6 ; p<0.0001 ) . In a subgroup analysis of those with lung cancer and lung function measured prior to the diagnosis of lung cancer ( n = 127 ) , we found a nonsignificant increase in COPD prevalence following diagnosis ( 56–61 % ; p = 0.45 ) . After controlling for important variables , the prevalence of COPD in newly diagnosed lung cancer cases was six-fold greater than in matched smokers ; this is much greater than previously reported . We conclude that COPD is both a common and important independent risk factor for lung cancer RATIONALE Identification of risk factors for lung cancer can help in selecting patients who may benefit the most from smoking cessation interventions , early detection , or chemoprevention . OBJECTIVE To evaluate whether the presence of emphysema on low-radiation-dose CT ( LDCT ) of the chest is an independent risk factor for lung cancer . METHODS The study used data from a prospect i ve cohort of 1,166 former and current smokers participating in a lung cancer screening study . All individuals underwent a baseline LDCT and spirometry followed by yearly repeat LDCT studies . The incidence density of lung cancer among patients with and without emphysema on LDCT was estimated . Stratified and multiple regression analyses were used to assess whether emphysema is an independent risk factor for lung cancer after adjusting for age , gender , smoking history , and the presence of airway obstruction on spirometry . RESULTS On univariate analysis , the incidence density of lung cancer among individuals with and without emphysema on LDCT was 25.0 per 1,000 person-years and 7.5 per 1,000 person-years , respectively ( risk ratio [ RR ] , 3.33 ; 95 % confidence interval [ CI ] , 1.41 to 7.85 ) . Emphysema was also associated with increased risk of lung cancer when the analysis was limited to individuals without airway obstruction on spirometry ( RR , 4.33 ; 95 % CI , 1.04 to 18.16 ) . Multivariate analysis showed that the presence of emphysema ( RR , 2.51 ; 95 % CI , 1.01 to 6.23 ) on LDCT but not airway obstruction ( RR , 2.10 ; 95 % CI , 0.79 to 5.58 ) was associated with increased risk of lung cancer after adjusting for potential cofounders . CONCLUSIONS Results suggest that the presence of emphysema on LDCT is an independent risk factor for lung cancer BACKGROUND COPD is an independent risk factor for lung cancer , especially in patients with mild to moderate disease . OBJECTIVE To determine if performing lung cancer screening in GOLD 1 and 2 COPD patients , results in reduced lung cancer mortality . METHODS This study compared patients with mild to moderate COPD from 2 cohorts matched for age , gender , BMI , FEV1 % , pack-yrs history and smoking status . The screening group ( SG ) had an annual low dose computed tomography ( LDCT ) . The control group ( CG ) was prospect ively followed with usual care .  Lung cancer incidence and mortality densities were compared between groups . RESULTS From an initial sample of 410 ( SG ) and 735 ( CG ) patients we were able to match 333 patients from each group . At the same follow-up time lung cancer incidence density was 1.79/100 person-years in the SG and 4.14/100 person-years in the CG ( p = 0.004 ) . The most frequent histological type was adenocarcinoma in both SG and CG ( 65 % and 46 % , respectively ) , followed by squamous cell carcinoma ( 25 % and 37 % , respectively ) . Eighty percent of lung cancers in the SG ( 16/20 ) were diagnosed in stage I , and all of CG cancers ( 35/35 ) were in stage III or IV . Mortality incidence density from lung cancer ( 0.08 vs. 2.48/100 person-years , p < 0.001 ) was lower in the SG . CONCLUSIONS This pilot study in patients with mild to moderate COPD suggests that screening with LDCT detects lung cancer in early stages , and could decrease lung cancer mortality in that high risk group . Appropriately design ed studies should confirm these important findings Breathlessness is a common symptom in patients with primary bronchial carcinoma and is often not well-controlled . Most patients are ex- or current smokers , and therefore are at high risk for co-existing chronic obstructive pulmonary disease ( COPD ) . The incidence of airflow obstruction in patients with bronchial carcinoma , its relation to breathlessness , and response to bronchodilator therapy was examined prospect ively . Fifty-seven consecutive patients attending our outpatient clinic with bronchial carcinoma diagnosed in the preceding 12 months were studied ( 22 female , 35 male , mean age 68.4 years ) . Spirometry was performed and breathlessness rated . Those with airflow obstruction ( FEV1:FVC < 65 % and FEV1 < 70 % predicted ) and who judged themselves to have moderate or severe breathlessness , were offered a trial of bronchodilator therapy . The response to regular inhaled fenoterol and ipratropium bromide by metered dose inhaler ( MDI ) and large volume spacer , and to regular nebulized salbutamol and ipratropium bromide was assessed by home peak flow recordings , spirometry and two subjective scores : ( a ) rating of breathlessness on a simple four-point scale , and ( b ) activity score of the St George 's Respiratory Question naire . There was very strong association between airflow obstruction and breathlessness . Twenty-eight patients ( 49 % ) had airflow obstruction , and we had breathlessness ratings on 26 of these patients of whom 18 ( 69 % ) had rated it as moderate or severe . Only four of the patients with airflow obstruction and breathlessness were using bronchodilator therapy . There was no significant difference in the mean age , time from diagnosis , tumour site , or smoking history between the groups with , and without , airflow obstruction . There was no association between cell type and the presence of airflow obstruction . ( ABSTRACT TRUNCATED AT 250 WORDS Our aim was to describe the characteristics of a case-series of  never-smoker small cell lung cancer ( SCLC ) cases . Cases of SCLC were selected from a prospect i ve , multicenter , hospital-based case – control study performed in Spain . Participants were never-smokers older than 30 years with an anatomo-pathological confirmation of primary lung cancer . We collected clinical and epidemiological variables according to the study 's protocol . We included 19 SCLC cases , 18 females ( 94.7 % ) , median age 75 years ( interquartile range ( IQR ) 70–80 years ) . Median residential radon concentration  was 195 Bq·m−3 ( IQR 130–229 Bq·m−3 ) . 10 patients had limited disease and nine had extended disease . Median survival was 242 days ( IQR 94–496 days ) ; 1- and 2-year survival were 36.8 % and 17.6 % , respectively . Survival was much higher for individuals with limited disease than for those with extended disease ( median 336 versus 235 days ; 1-year survival 50 % versus 22.2 % and 2-year survival 27 % versus 0 % , respectively ) . Performance status at diagnosis was closely related to survival . SCLC is an infrequent , highly aggressive disease in never-smokers . Survival is poor , even for limited disease . Age at diagnosis in SCLC is higher than that observed for never-smokers with adenocarcinoma .  Residential radon exposure is higher than the action levels recommended by the World Health Organization . Small cell lung cancer in never-smokers has a poor survival and is diagnosed at older ages than other lung cancers OBJECTIVES Several studies have identified airflow obstruction as a risk factor for lung cancer independent of smoking history , but the risk associated with the presence of radiographic evidence of emphysema has not been extensively studied . We proposed to assess this risk using a quantitative volumetric CT scan analysis . METHODS Sixty-four cases of lung cancer were identified from a prospect i ve cohort of 1,520 participants enrolled in a spiral CT scan lung cancer screening trial . Each case was matched to six control subjects for age , sex , and smoking history . Quantitative CT scan analysis of emphysema was performed . Spirometric measures were also conducted . Data were analyzed using conditional logistic regression making use of the 1:6 set groups of 64 cases and 377 matched control subjects . RESULTS Decreased FEV(1 ) and FEV(1)/FVC were 
    Output:
    
Both COPD and emphysema seem to increase the risk of developing lung cancer , being this risk higher for smokers with heavier tobacco consumption .