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J. Mayo

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    O06 - Cancer Control and Epidemiology I (ID 135)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Prevention & Epidemiology
    • Presentations: 1
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      O06.06 - Factors Associated with Smoking Cessation in Participants of The Pan Canadian Early Lung Cancer Study (ID 1469)

      10:30 - 12:00  |  Author(s): J. Mayo

      • Abstract
      • Presentation
      • Slides

      Lung cancer screening programs provide unique opportunities to facilitate smoking cessation in smokers who participate in these programs. However, the effects of screening on motivation to quit might be mediated or modified by other variables. Identifying the participants more likely to quit will allow rapid application of smoking cessation resources to these participants, while those least likely to quit can be afforded experimental interventions. The aim of our study was to assess the impact of lung cancer screening on smoking cessation in current smokers at the time of enrollment and to identify factors that were associated with quitting smoking in this screening population.

      Using data collected from the Pan-Canadian Study of Early Detection of Lung Cancer, both univariate and multivariable logistic regression analysis was used to identify predictors of smoking cessation among current smokers at enrolment. Smoking cessation was defined as quitting for at least a 6 month period, occurring anytime after enrolment.

      We analyzed baseline and follow-up questionnaires of 2320 participants, of which 1419 were current smokers. Of these 1419 patients, 392 (27.8%) met the definition of smoking cessation during a median of two annual follow-up visits. In both univariate and multivariable (MV) analysis, greater smoking cessation was associated with four factors: (i) having a diagnosis of lung cancer at any time during the screening process, with a MV Odds ratio (OR) of quitting of 2.4 (95%CI: 1.1-5.0); (ii) lower and medium nicotine addiction as assessed by the Fagerström Nicotine Dependence Scale Score, with MV-ORs of 3.2 (95%CI: 2.2-4.6) and 1.4 (95%CI: 0.9-2.0), respectively; (iii) having higher education, with MV-OR: 1.4 (95%CI: 1.1-1.9); and (iv) having an earlier age of onset of regular alcohol intake, with MV-OR of 1.11 (95%CI: 1.02-1.21) per 5 year decrease in age. Smoking cessation was also associated with (i) previous attempts of quitting [UV-OR 1.8 (95%CI: 1.2-2.7)], willingness to quit smoking within the next month (at baseline screening) [UV-OR 2.2 (95%CI: 1.8-2.9)] or within the next 6 months after baseline screening [UV-OR 1.8 (95%CI: 1.3.-2.4)]. Second-hand smoking exposure, including exposure as a child, or as an adult at work, at home, privately with friends, or in public settings, or a cumulative index of these different exposures, was not associated with smoking cessation. Presence of potential index symptoms for lung disease, including shortness of breath, cough (both dry and productive), hoarseness, audible wheezing or even chest pain, was not associated with an increased chance of smoking cessation.

      The diagnosis of a new lung cancer had a major positive impact on screening participants quitting smoking, as were factors such as lower nicotine dependence, higher education, earlier starting alcohol drinking age, and willingness to quit. Whether a new lung cancer diagnosis triggered additional efforts by clinicians to help the person quit will be explored further. Individual lung symptoms and secondhand smoke exposure were not associated with smoking cessation. (Geoffrey Liu and Martin Tamemmagi are co-senior authors)

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    P3.20 - Poster Session 3 - Early Detection and Screening (ID 174)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P3.20-011 - Lung density versus emphysema as predictor of malignancy risk of pulmonary nodules detected on first screening CT (ID 3353)

      09:30 - 16:30  |  Author(s): J. Mayo

      • Abstract

      The association between chronic obstructive pulmonary disease (COPD) and lung cancer has been previously reported. However, the mechanism whereby emphysema (a destructive process) promotes lung carcinogenesis (a proliferative process) has not been adequately explained. Emphysema is associated with lower lung density while lung inflammation is associated with increase in lung density. We hypothesized that lung density and emphysema are independent predictors of malignancy risk of lung nodules found on screening low dose spiral CT (LDCT).

      Image analysis was performed on a subset of LDCT scans (120 kVp, 40 mAs) from the Pan Canadian Early Detection of Lung Cancer Study and the BCCA Lung Health Study using the VIDA Diagnostics CT image analysis software Pulmonary Workstation 2. The lobe with the pulmonary nodule was first segmented. The average lung density surrounding the nodule was measured. Emphysema severity was defined as percentage of the lobe with -950 Hounsfield Units (HU). Multivariate logistic regression analysis was performed to determine if lung density and degree of emphysema were independently associated with malignant lung nodules.

      A total of 161 subjects with lung nodules ≤20 mm were studied. The clinical and CT characteristics are shown in the Table 1. Table 1. Study variables by lung cancer status

      No Cancer Cancer P-value
      N= 95 66
      Age 64±5 63±6 0.52
      Gender : Men: Women 53% : 47% 38% : 62% 0.078
      Current: Former smoker 61% : 39% 45% : 55% 0.051
      Family history % 21% 38% 0.022
      Nodule diameter 10.5 ± 3.0 12.9 ± 4.1 <0.001
      Nodule Type – solid 53% 50%
      - part solid 11% 29% 0.003
      - Non-solid 37% 20%
      Nodule location (upper versus middle or lower) 45% 65% 0.016
      Spiculation (%) 18% 39% 0.017
      Emphysema (visual score) % present 67% 78% 0.152
      Density of lobe with nodule -848±32 -837±32 0.024
      % emphysema in lobe with nodule 9.3%±9.7 7.1%±6.9 0.09
      While the presence of emphysema of any grade in both lungs by visual score was higher in the lung cancer group (78% versus 67%), the difference was not statistically significant in the univariate or multivariate analysis. Quantitative measurement of emphysema severity (area with -950 HU) in the same lobe where the lung nodule located showed that the degree of emphysema was less in patients with lung cancer (7.1% versus 9.3 %, P = 0.041 in the final multivariable logistic regression model consisting of family history, nodule size, type and spiculation). Lung density surrounding the lung nodule was significantly higher in the lung cancer group compared to the benign nodule group in univariate analysis (P = 0.024) but not in multivariable analysis.

      Our results suggest lung inflammation as reflected by increase in lung density may be a more important factor in lung carcinogenesis while emphysema may be more of a dosimeter for lung damage by tobacco smoke exposure. Further studies in a larger dataset are being performed to determine the incremental value of lung density in predicting the malignancy risk of lung nodules ≤ 2cm detected by screening LDCT.