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A. Dirksen



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    O23 - Imaging and Screening (ID 125)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      O23.02 - Positron emission tomography (PET) in lung cancer screening<br /> - Final results after a 5 year screening programe. (ID 1021)

      16:25 - 16:35  |  Author(s): A. Dirksen

      • Abstract
      • Presentation
      • Slides

      Background
      PET is a useful tool in the diagnostic workup of lung cancer. However, its role in lung cancer screening with low dose Computed Tomography (CT), in which small sized nodules are detected, is still to be determined. We present final PET results from the 5 year (2005-2010) randomized Danish Lung Cancer Screening Trial (DLCST).

      Methods
      DLCST participants with indeterminate nodules mostly between 5 and 15 mm were referred for a 3-month rescan. Between the initial scan and the 3-month rescan, participants were also referred for a PET scan. Uptake on PET was categorized as most likely benign or malignant on a scale from I to IV). Receiver operating characteristic (ROC) analyses were used to determine the sensitivity and specificity of PET. Resected nodules and indolent nodules (i.e. stable for at least 2 years) were included, and the latter was categorized as benign. Nodules were only included once in the study, thus repeat PET scans were excluded.

      Results
      A total of 90 nodules were included, 50% men, mean age 67 years (58-79), prevalence of lung cancer was 38% (35/90). Mean follow-up time for benign non-resected nodules was approx. 2.8 years in screening. Clinical follow-up in central digital medical logs was done for all participants in 2013. The sensitivity and specificity of PET was 66% and 91%, respectively, with cut-off points for malignancy at PET>II (i.e. categorized as possibly or probably malignant at PET). The positive predictive value was 82% (23/28) and negative predictive value was 81% (50/62). 12 PET results were false negative, and of these 75% (9/12) were either ground glass nodules or partly solid nodules. Figure 1

      Conclusion
      PET is a valuable tool in lung cancer screening; our results show fair sensitivity and high specificity in a trial with long time follow-up of benign nodules. False negative PET results were found in non-solid nodules. We recommend PET as an integrated part of future lung cancer screening programs.

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    P1.19 - Poster Session 1 - Imaging (ID 179)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P1.19-006 - Predictors of nodule malignancy in the Danish Lung Cancer Screening Trial (DLCST) (ID 2172)

      09:30 - 09:30  |  Author(s): A. Dirksen

      • Abstract

      Background
      Pulmonary nodules are detected more frequently than ever in both clinical and screening settings. Timely and correct suspicion of malignancy is of great importance in the subsequent management of the nodules. We present data on pulmonary nodule growth and participants baseline characteristics to determine predictors of malignancy.

      Methods
      In DLCST, 4,104 current and former smokers, with a history of at least 20 pack years and age between 50-70 years, were randomized to either five annual multi-slice low-dose CT screenings or no screening. All participants had an annual visit to the screening clinic where lung function tests and questionnaires concerning health, lifestyle, smoking habits etc. were performed. The scans were read by two chest radiologists who recorded the location and size of any nodules. Nodules of diameters between 5-15 mm were considered indeterminate, and rescanned after three months. Participants with nodules larger than 15 mm were referred to diagnostic workup, as were those with growing nodules. Lung cancer was diagnosed by pathological evaluation. Using volumetric software solid and nonsolid/partsolid nodules were segmented and followed. Only visually correct segmented nodules that were present more than one year were included. Doubling times of mass, volume and diameter from the first to the last record of the nodule were calculated. We performed logistic regression analysis with malignancy as the outcome and baseline characteristics, nodule type and growth measurements as explanatory variables.

      Results
      975 nodules in 618 participants were included. 31 nodules (3%) were diagnosed as lung cancers. 10(33%) of the malignant nodules were nonsolid/partsolid. Fig. 1 shows histograms of growth measurements. Fig. 2 show the logistic regression analysis. In both cases FEV1 and Mass Doubling Times predicted malignancy significantly.Figure 1Figure 2

      Conclusion
      Growth rates measured by volumetric software and FEV1 are powerful predictors for malignancy when a pulmonary nodule is present in a low dose chest CT scan.