The correlation of emphysema or airway obstruction with the risk of lung cancer: a matched case-controlled study

Previous lung diseases and lung cancer risk: a systematic review and meta-analysis

BACKGROUND

In order to review the epidemiologic evidence concerning previous lung diseases as risk factors for lung cancer, a meta-analysis and systematic review was conducted.

METHODS

Relevant studies were identified through MEDLINE searches. Using random effects models, summary effects of specific previous conditions were evaluated separately and combined. Stratified analyses were conducted based on smoking status, gender, control sources and continent.

RESULTS

A previous history of COPD, chronic bronchitis or emphysema conferred relative risks (RR) of 2.22 (95% confidence interval (CI): 1.66, 2.97) (from 16 studies), 1.52 (95% CI: 1.25, 1.84) (from 23 studies) and 2.04 (95% CI: 1.72, 2.41) (from 20 studies), respectively, and for all these diseases combined 1.80 (95% CI: 1.60, 2.11) (from 39 studies). The RR of lung cancer for subjects with a previous history of pneumonia was 1.43 (95% CI: 1.22-1.68) (from 22 studies) and for subjects with a previous history of tuberculosis was 1.76 (95% CI=1.49, 2.08), (from 30 studies). Effects were attenuated when restricting analysis to never smokers only for COPD/emphysema/chronic bronchitis (RR=1.22, 0.97-1.53), however remained significant for pneumonia 1.36 (95% CI: 1.10, 1.69) (from 8 studies) and tuberculosis 1.90 (95% CI: 1.45, 2.50) (from 11 studies).

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.

Effect of emphysema on lung cancer risk in smokers: a computed tomography-based assessment

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 prospective 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 standard 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.

A quantitative method for estimating individual lung cancer risk

RATIONALE AND OBJECTIVES

Lung cancer is caused primarily by repeated exposure to carcinogenic particulate matter and noxious gasses with high particulate deposition localized to airway bifurcations and the lung periphery. The quantitative measurement and analysis of these sites has the potential to stratify lung cancer risk. The aim of this preliminary study was to assess the performance of a new method for estimating individual lung cancer risk based on the analysis of airway bifurcations on high-resolution (HR) computed tomographic (CT) scanning and spirometry.

MATERIALS AND METHODS

One hundred eight subjects with spirometry and thin-slice CT data were selected from a CT screening study including 15 patients with early lung cancer and 93 age-matched and pack-year-matched controls. A subset of seven patients with cancer and 72 controls were scanned with 1-mm CT slice thickness, representing an HR case subset. A quantitative lung cancer risk index method was developed on the basis of airway bifurcation x-ray attenuation combined with the ratio of forced expiratory volume in 1 second to forced vital capacity. Cochran-Mantel-Haenszel and conditional logistic regression tests were used to analyze performance.

RESULTS

Cochran-Mantel-Haenszel crude analysis revealed a cancer detection sensitivity and specificity of 67% and 72% for all cases and 100% and 73% for the HR case subset, respectively. Conditional logistic regression showed that a 0.0328 increase in lung cancer risk index was associated with odds ratios of 1.84 (95% confidence interval, 1.18-2.85) for the full data set (P = .0067) and 2.89 (95% confidence interval, 1.02-8.19) for the HR subset (P = .0467).

CONCLUSIONS

A preliminary evaluation of a new lung cancer risk estimation method based on thin slice CT and spirometry showed a statistically significant association with lung cancer.

Are airflow obstruction and radiographic evidence of emphysema risk factors for lung cancer? A nested case-control study using quantitative emphysema analysis

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 prospective 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 significantly associated with a diagnosis of lung cancer with ORs of 1.15 (95% CI, 1.00-1.32; P = .046) and 1.29 (95% CI, 1.02-1.62; P = .031), respectively. The quantity of radiographic evidence of emphysema was not found to be a significant risk for lung cancer with OR of 1.042 (95% CI, 0.816-1.329; P = .743). Additionally, there was no significant association between severe emphysema and lung cancer with OR of 1.57 (95% CI, 0.73-3.37).

CONCLUSIONS

We confirm previous observations that airflow obstruction is an independent risk factor for lung cancer. The absence of a clear relationship between radiographic evidence of emphysema and lung cancer using an automated quantitative volumetric analysis may result from different population characteristics than those of prior studies, radiographic evidence of emphysema quantitation methodology, or absence of any relationship between emphysema and lung cancer risk.

3D-CT volumetry of the lung using multidetector row CT: comparison with pulmonary function tests

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate the accuracy of measurements of lung volumes reconstructed using three-dimensional computed tomographic (CT) imaging from thin-section multidetector-row CT images compared to standard pulmonary function testing.

MATERIALS AND METHODS

Preoperative three-dimensional CT images and pulmonary function test results of 64 patients with solitary pulmonary nodules who were considered candidates for lung resection were reviewed. On the three-dimensional CT images, total lung capacity (TLC(CTV)), emphysematous lung capacity (ELC(CTV)), and normal lung capacity (NLC(CTV)) were calculated. Total lung capacity (TLC), vital capacity, and forced expiratory volume in 1 second were measured using spirometry.

RESULTS

There was a strong positive correlation between estimated TLC(CTV) and measured TLC values (r = 0.87, P < .001). Estimated ELC(CTV) at the threshold value of -900 Hounsfield units was negatively correlated with forced expiratory volume in 1 second (r = -0.56, P < .001). NLC(CTV) values were more strongly correlated with vital capacity values than TLC(CTV) values (r = 0.74, P < .001).

CONCLUSIONS

Lung volume calculated using three-dimensional CT volumetry was well correlated with lung volume measured using spirometry. Three-dimensional CT volumetry can be used to evaluate pulmonary function.

Association of radiographic emphysema and airflow obstruction with lung cancer

RATIONALE

To study the relationship between emphysema and/or airflow obstruction and lung cancer in a high-risk population.

OBJECTIVE

We studied lung cancer related to radiographic emphysema and spirometric airflow obstruction in tobacco-exposed persons who were screened for lung cancer using chest computed tomography (CT).

METHODS

Subjects completed questionnaires, spirometry, and low-dose helical chest CT. CT scans were scored for emphysema based on National Emphysema Treatment Trial criteria. Multiple logistic regressions estimated the independent associations between various factors, including radiographic emphysema and airflow obstruction, and subsequent lung cancer diagnosis.

MEASUREMENTS AND MAIN RESULTS

Among 3,638 subjects, 57.5, 18.8, 14.6, and 9.1% had no, trace, mild, and moderate-severe emphysema, and 57.3, 13.6, 22.8, and 6.4% had no, mild (Global Initiative for Chronic Obstructive Lung Disease [GOLD] I), moderate (GOLD II), and severe (GOLD III-IV) airflow obstruction. Of 3,638 subjects, 99 (2.7%) received a lung cancer diagnosis. Adjusting for sex, age, years of cigarette smoking, and number of cigarettes smoked daily, logistic regression showed the expected lung cancer association with the presence of airflow obstruction (GOLD I-IV, odds ratio [OR], 2.09; 95% confidence interval [CI], 1.33-3.27). A second logistic regression showed lung cancer related to emphysema (OR, 3.56; 95% CI, 2.21-5.73). After additional adjustments for GOLD class, emphysema remained a strong and statistically significant factor related to lung cancer (OR, 3.14; 95% CI, 1.91-5.15).

CONCLUSIONS

Emphysema on CT scan and airflow obstruction on spirometry are related to lung cancer in a high-risk population. Emphysema is independently related to lung cancer. Both radiographic emphysema and airflow obstruction should be considered when assessing lung cancer risk.

Assessing the relationship between lung cancer risk and emphysema detected on low-dose CT of the chest

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 prospective 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.

Computed Tomography–Diagnosed Emphysema, Not Airway Obstruction, Is Associated with the Prognostic Outcome of Early-Stage Lung Cancer

PURPOSE

Because both emphysema and lung cancer can arise from biological damage caused by cigarette smoking, we investigated if the development of emphysema is associated with the clinical features of smoker's lung cancer.

EXPERIMENTAL DESIGN

The subjects were a consecutive series of 100 smokers who underwent lobectomy with hilar and mediastinal dissection for clinical stage I non-small cell lung cancer. We studied the relationship between the presence or absence of emphysema at the onset of the lung cancer and clinicopathologic features. Emphysema was diagnosed by measuring the low-attenuation area using computed tomography densitometry.

RESULTS

There were no differences in clinicopathologic variables, including the degree of smoking exposure between the patients with (n=58) and those without (n=42) emphysema, although male gender and airflow limitation were predominant in the patients with emphysema. The presence of emphysema, but neither male gender nor airflow limitation, adversely affected both overall and disease-specific survival. According to Cox regression analysis, emphysema was an independent prognosticator among age, gender, degree of smoking exposure, tumor size, nodal status, histologic subtype, histologic grade, and microvessel invasion. These results were stabilized by a bootstrap sampling model.

CONCLUSIONS

Computed tomography-diagnosed emphysema, but not airway obstruction, is associated with poor prognosis in smokers with early-stage lung cancer. Thus, routine computed tomography densitometry in smokers with lung cancer should be mandatory.

Impaired lung function and lung cancer incidence in a cohort of Swedish construction workers

BACKGROUND

Although impaired lung function in general has been associated with an increased risk of lung cancer, past studies typically have not attempted to investigate separately the obstructive and restrictive components of respiratory impairment. To deal with this question further, data from a large (n = 176 997) cohort of male Swedish construction workers, for whom spirometry measurements before follow-up were available, were analysed.

METHODS

Cancer incidence for 1971-2001 was obtained through linkage with the national cancer registry. Using a modification of the Global Initiative for Chronic Obstructive Lung Disease criteria for chronic obstructive pulmonary disease (COPD), subjects were classified into five categories of lung function: normal, mild COPD, moderate COPD, severe COPD and restrictive lung disease (RLD). Rate ratios (RR) and 95% confidence intervals (CI) for lung cancer across lung function categories were calculated using Poisson regression, adjusted for age and smoking. Other end points (histological types of lung cancer, non-lung tobacco-related cancers, other cancers, total mortality) were also investigated.

RESULTS

834 incident cases of lung cancer were identified. Increased rates of lung cancer were observed for both COPD (mild: RR 1.5, 95% CI 1.2 to 1.9; moderate/severe: RR 2.2, 95% CI 1.8 to 2.7) and RLD (RR 2.0, 95% CI 1.6 to 2.5) relative to normal lung function. These associations did not meaningfully change on applying follow-up lag times of 5, 10 and 15 years after spirometry. When analysed by histological type, associations with both COPD and RLD were stronger for squamous cell carcinoma and small cell carcinoma, and weaker for adenocarcinoma. Both COPD and RLD were associated with increased rates of total mortality.

CONCLUSIONS

Obstructive and restrictive impairments in lung function are associated with increased lung cancer risk.

Improvement in household stoves and risk of chronic obstructive pulmonary disease in Xuanwei, China: retrospective cohort study

OBJECTIVE

To test whether improvement in household coal stoves affected the incidence of chronic obstructive pulmonary disease (COPD) in Xuanwei County, China.

DESIGN

Retrospective cohort study (follow-up 1976-92) comparing incidence of COPD between groups with and without chimneys.

PARTICIPANTS

20,453 people born into homes with unvented coal stoves;16,606 (81.2%) subsequently changed to stoves with chimneys.

INTERVENTION

Installation of a chimney in households in which unvented stoves had been used previously.

RESULTS

Installation of a chimney was associated with distinct reduction in the incidence of COPD. Compared with people who did not have chimneys, the Cox-modelled risk ratio (relative risk) was 0.58 (95% confidence interval 0.49 to 0.70, P < 0.001) in men and 0.75 (0.62 to 0.92, P = 0.005) in women. Modelled risk ratios were robust to different Cox model specifications. Relative risks decreased with time since stove improvement. In both sexes, the reduction in risk became unequivocal about 10 years after stove improvement.

CONCLUSIONS

In Xuanwei, incidence of COPD decreased markedly after household coal stoves were improved.

Quality of life after tailored combined surgery for stage I non–small-cell lung cancer and severe emphysema

BACKGROUND

We analyzed the early and long-term quality of life changes occurring in 16 patients undergoing tailored combined surgery for stage I non-small-cell lung cancer (NSCLC) and severe emphysema.

METHODS

Mean age was 65 +/- 5 years. All patients had severe emphysema with severely impaired respiratory function and quality of life. Tumor resection was performed with sole lung volume reduction (LVR) in 5 patients, separate wedge resection in 3 patients, segmentectomy in 2 patients, and lobectomy in 6 patients. A bilateral LVR was performed in 5 patients. Quality of life was assessed at baseline and every 6 months postoperatively by the Short-form 36 (SF-36) item questionnaire.

RESULTS

Mean follow-up was 44 +/- 21 months. All tumors were pathologic stage I. There was no hospital mortality nor major morbidity. Significant improvements occurred for up to 36 months in the general health (p = 0.02) domain and for up to 24 months in physical functioning (p = 0.02), role physical (p = 0.005), and general health (p = 0.01) SF-36 domains. Associated improvements regarded dyspnea index (-1.3 +/- 0.6) forced expiratory volume in one second (+0.28 +/- 0.2L), residual volume (-1.18 +/- 0.5L) and 6-minute-walking test distance (+86 +/- 67 m). Actuarial 5-year survival was similar to that of patients with no cancer undergoing LVRS during the same period (68% vs 82%, p = not significant).

CONCLUSIONS

Our study suggests that selected patients with stage I NSCLC and severe emphysema may significantly benefit from tailored combined surgery in terms of long-term quality of life and survival.