***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : We evaluated the relationship of Chlamydia pneumoniae infection with prospect i ve lung cancer risk  using traditional serologic markers [ microimmunoflourescence ( MIF ) IgG and IgA antibodies ] and Chlamydia heat shock protein-60 ( CHSP-60 ) antibodies , a marker for chronic chlamydial infection . Methods : We conducted a nested case-control study ( 593 lung cancers and 671 controls ) within the screening arm of the Prostate , Lung , Colorectal , and Ovarian Cancer Screening Trial ( N = 77,464 ) . Controls were matched to cases by age , sex , r and omization year , follow-up time , and smoking ( pack-years of smoking , time since quitting ) . We assessed C. pneumoniae seropositivity and endpoint antibody titers ( IgG and IgA against C. pneumoniae elementary bodies and IgG against CHSP-60 ) . Results : C. pneumoniae seropositivity by microimmunoflourescence IgG or IgA antibodies was not associated with lung cancer [ odds ratio of 0.88 and 95 % confidence interval ( 95 % CI ) of 0.69 - 1.13 for IgG ; odds ratio of 0.98 and 95 % CI of 0.75 - 1.27 for IgA ] . In contrast , individuals seropositive for CHSP-60 IgG antibodies had significantly increased lung cancer risk ( odds ratio , 1.30 ; 95 % CI , 1.02 - 1.67 ) , and risk increased with increasing antibody titers ( P trend = 0.006 ) . CHSP-60–related risk did not differ significantly by lung cancer histology , follow-up time , or smoking . CHSP-60 seropositivity was associated with increased risk 2 to 5 years before lung cancer diagnosis ( odds ratio , 1.77 ; 95 % CI , 1.16 - 2.71 ; P trend = 0.006 ) , thus arguing against reverse causality . Conclusions : CHSP-60 seropositivity and elevated antibody titers were associated with significantly increased risk for subsequent lung cancer , supporting an etiologic role for C. pneumoniae infection in lung carcinogenesis . Impact : Our results highlight the potential for lung cancer risk reduction through treatments targeted toward C. pneumoniae infections and chronic pulmonary inflammation . Cancer Epidemiol Biomarkers Prev ; 19(6 ) ; 1498–505 . © 2010 AACR Chinese women in Hong Kong have among the highest incidence and mortality of lung cancer in the world , in spite of a low prevalence of smoking . We carried out this population -based case – control study to evaluate the associations of previous lung disease and family cancer history with the occurrence of lung cancer among them . We selected 212 cases that were newly diagnosed with primary lung cancer , and r and omly sample d 292 controls from the community , frequency matched by age group . All the cases and controls were lifetime nonsmokers . We estimated the main effects of preexisting asthma , pulmonary tuberculosis , pneumonia , chronic bronchitis , and family lung/all cancer history , using unconditional logistic regression , accounting for various potential risk factors and confounders . All of the previous lung diseases , except chronic bronchitis , were related to an elevated risk for lung cancer , and the association with asthma was significant . Those who had more than one previous lung disease tended to be at higher risk than those with only one of them . Positive family history of any cancer was associated with over 2-fold risk than negative family history . The joint effect of positive history of previous pulmonary diseases and positive family cancer history appeared to be additive , indicating the two factors acted independently . The results support an etiological link of preexisting lung disease and family cancer history to the risk of 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 thought to be more prevalent among men than women , a finding usually attributed to higher smoking rates and more frequent occupational exposures of significance for men . However , smoking prevalence has increased among women and there is evidence that women may be more susceptible to the adverse pulmonary function effects of smoking than men . There may also be underdiagnosis and misdiagnosis of COPD in both sexes because objective measures of lung function are underused . OBJECTIVES We undertook the present study to determine if there is gender bias in the diagnosis of COPD , such that women are less likely than men to receive a diagnosis of COPD . We also attempted to determine if underuse of lung function measurements was a factor in any bias detected . METHODS We surveyed a r and om sample of 192 primary -care physicians ( 96 American and 96 Canadian ; 154 men and 38 women ) using a  hypothetical case presentation and a structured interview . The case of cough and dyspnea in a smoker was presented in six versions differing only in the age and sex of the patient . After presentation of the history and physical findings , physicians were asked to state the most probable diagnosis and to choose the diagnostic studies needed . Physicians were then presented with spirometric findings of moderate or severe obstruction without significant bronchodilator response , and the questions repeated . Finally , the negative outcome of an oral steroid trial was described . RESULTS Initially , COPD was given as the most probable diagnosis significantly more often for men than women ( 58 % vs 42 % ; p < 0.05 ) . The likelihood of a COPD diagnosis increased significantly and initial differences between sexes decreased as objective information was provided . After spirometry , COPD diagnosis rates for men and women were 74 % vs 66 % ( p = not significant ) ; after the steroid trial 85 % vs 79 % ( p = not significant ) . Only 22 % of physicians would have requested spirometry after the initial presentation . CONCLUSIONS In North America , primary -care physicians underdiagnosed COPD , particularly in women . Spirometry reduces the risk of underdiagnosis and gender bias but is underused Abstract Objectives : While 75 - 90 % of people who develop lung cancer are smokers , only a small proportion of smokers develop lung cancer . Identifying factors that increase a smoker 's risk of developing lung cancer may help scientists to better underst and the etiology of lung cancer and more effectively target high-risk groups for screening . Methods : Information on physician-diagnosed non-malignant lung diseases [ asbestosis , asthma , chronic bronchitis or emphysema ( CB/E ) , pneumonia , and tuberculosis ] was obtained at baseline from 17,698 men and women involved in CARET , a r and omized lung cancer prevention trial of beta-carotene and vitamin A among heavy smokers and asbestos-exposed workers .  Hazard ratios for lung cancer were estimated through Cox regression models , after controlling for potential confounding factors , included smoking . Analyses were restricted to former and current smokers . Results : During a median follow up of 9.1 years , 1028 cases of lung cancer occurred . Those who developed lung cancer were more likely to report a history of CB/E than controls ( adjusted HR = 1.29 , 95 % CI : 1.09 - 1.53 ) . In subgroup analyses , the association between a history of CB/E and lung cancer was stronger for those who were younger at diagnosis/reference , men in the heavy smoker cohort , former smokers , and those with squamous cell carcinomas . There was little association between a history of other lung diseases and lung cancer . Conclusions : Smokers with a history of CB/E may be at higher risk of developing lung cancer , independent of their smoking history Small cell carcinoma of the lung ( SCLC ) occurs most frequently in heavy smokers , yet exhibits a lesser predominance among men than other smoking-associated lung cancers . Incidence rates have increased more rapidly in women than men and at a faster rate among women than other cell types . To investigate the importance of smoking and other risk factors , a case-control study of SCLC in women was conducted . A total of 98 women with primary SCLC and 204 healthy controls , identified by r and om-digit dialing and frequency matched for age , completed telephone interviews .  Data collected include demographics , medical history , family cancer history , residence history , and lifetime smoking habits . Odds ratios ( ORs ) and 95 % confidence intervals ( 95 % CI ) were calculated using logistic regression analysis . Risk for small cell carcinoma in women is strongly associated with current use of cigarettes . Ninety-seven of 98 cases had smoked cigarettes ; 79 % of cases were current smokers and 20 % were former smokers at the time of diagnosis compared to 13 % current and 34 % former smokers among controls . The ORs associated with smoking are 108.7 ( 95 % CI 14.8 - 801 ) for ever-use of cigarettes , 278.9 ( 95 % CI 37.0 - 2102 ) for current smoking , and 31.5 ( 95 % CI 4 . 1 - 241 ) for former smoking . Risk increases steeply with pack-years of smoking and decreases with duration of smoking cessation . After adjusting for age , education , and lifetime smoking history , medical history of physician-diagnosed respiratory disease including chronic bronchitis , emphysema , pneumonia , tuberculosis , asthma , and hay fever is not associated with a significant increase in lung cancer risk . Employment in blue collar , service , or other high risk occupations is associated with a two to three-fold non-significant increase in risk for small cell carcinoma after adjusting for smoking BACKGROUND China has 1.4 million new cases of tuberculosis every year , more than any country except India . A new tuberculosis control project based on short-course chemotherapy was introduced in half the country in 1991 , after a national survey of tuberculosis prevalence in 1990 . Another survey was done in 2000 to re-evaluate the national tuberculosis burden , providing the opportunity to assess the effect of the control project . METHODS The survey in 2000 identified 375599 eligible individuals at 257 investigation points chosen from all 31 mainl and provinces by stratified r and om sampling . Children ( aged 0 - 14 years ) were suspected of having tuberculosis if they had an in duration of 10 mm or greater after a tuberculin skin test , and an abnormal fluorograph . Adults were suspected if they had a persistent cough , abnormal fluorograph , or both . Tuberculosis was diagnosed by chest radiograph , sputum-smear microscopy , and culture . FINDINGS 365097 people were examined ( 97 % of those eligible ) .  Prevalences of pulmonary , culture-positive , and smear-positive tuberculosis in 2000 were 367 ( 95 % CI 340 - 397 ) , 160 ( 144 - 177 ) , and 122 ( 110 - 137 ) per 100000 population , respectively . Between 1990 and 2000 , prevalences of these three forms of the disease had fallen , respectively , by 32 % ( 5 - 68 ) , 37 % ( 7 - 66 ) , and 32 % ( 9 - 51 ) more in areas in which the project was implemented than in non-project areas . For culture-positive disease , a 30 % ( 9 - 48 ) reduction was directly attributable to the project . INTERPRETATION Between 1991 and 2000 , prevalence of tuberculosis was reduced significantly in areas of China by use of short-course chemotherapy following WHO guidelines . We estimate that in 2000 , in a population of more than half a billion , there were 382000 fewer prevalent culture-positive 
    Output:
    
Conclusions Previous lung diseases are associated with an increased risk of lung cancer with the evidence among never smokers supporting a direct relationship between previous lung diseases and lung cancer