Author of

• 12812

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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
  • Moderators:
  • Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 12823

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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 - 09:30  |  Author(s): H. Coxson
    • Abstract

    Background
    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).

    Methods
    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.

    Results
    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.

    Conclusion
    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.