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Samuel Miguel Aguayo



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    ES08 - Critical Concerns in Screening (ID 11)

    • Event: WCLC 2019
    • Type: Educational Session
    • Track: Screening and Early Detection
    • Presentations: 1
    • Now Available
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      ES08.04 - Management Algorithms (Now Available) (ID 3194)

      13:30 - 15:00  |  Author(s): Samuel Miguel Aguayo

      • Abstract
      • Presentation
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      Abstract

      Introduction

      Clinical management decisions arising from the first, baseline round of screening for lung cancer are most challenging, as nodules that are seen for the first time may have accumulated over a lifetime and almost all of them are of no clinical concern [1]. In contrast, new or changing findings on subsequent annual repeat low-dose CT scans (LDCTs) have much greater clinical significance.

      Efficiency is particularly important in the baseline round in order to minimize unnecessary harms caused by work-up within the 12 months after the baseline LDCT. Potential workup includes surgery, biopsies, and diagnostic tests requiring intravenous injection (e.g., PET scans, contrast CT). Biopsies and surgery have greater risks than LDCT, and thus the management protocols should aim to minimize these higher risk procedures as much as possible [2]. It is also important not to discourage participants undergoing the baseline round from future participation in annual rounds as these provide the real benefit of annual LDCT screening.

      Methods

      We compared the efficiency of three published baseline LDCT screening protocols [2], the International Early Lung Cancer Action Program (I-ELCAP) [3], American College of Radiology (ACR)-LungRADS [4], and the European Consortium protocols [5] for participants 50 years of age or older with at least 20 pack-years of smoking.

      The three protocols provide recommendations for immediate workup, 3-month and 6-month LDCT as shown in Table 1 [1]. The three protocols use the diameter of the entire solid and nonsolid non-calcified nodule (NCN), but differ for part-solid NCNs. For part-solid NCNs, I-ELCAP uses the diameter of the solid component [6], while ACR-LungRADS uses both the entire diameter of the part-solid NCN as well as the diameter of its solid component. The European Consortium protocol determines the volume of a solid NCN using their software [5], but also specifies the equivalent diameter values for the entire part-solid and nonsolid NCNs as volumetric measurements for these are problematic as was recognized [5]. Measurement error and rounding of measurements are also an important consideration [7,8].

      Efficiency was defined as an efficiency ratio (ER): the number of participants recommended for a particular workup divided by the resulting number of participants diagnosed with lung cancer [2]. An ER of 1 would mean that each recommended workup resulted in a diagnosis of lung cancer. An optimum ER has not been established for lung cancer, but it has been suggested that for lung surgery, a rate of 10% for non-malignant resections is desirable (9), this would be an ER of 1.1. In breast cancer biopsies which have a much lower risk than lung biopsies, it is recommended that 40% of biopsies should be negative to ensure sufficient workup to diagnose breast cancers early enough this would represent an ER of 1.4

      Results

      Table 1 provides the frequency of following the recommendations, the number of cancers diagnosed and the ER for each protocol. In summary, I-ELCAP recommendations had the lowest ER values for overall, immediate and delayed workup, and for potential biopsies.

      Discussion

      All three protocols used LDCT to guide evaluation of NCNs, particularly for the smaller NCNs. LDCT is a very low risk test as it requires no injection of contrast, the radiation dose is deemed “small” and “hypothetical” by the American Association of Physicists in Medicine [10], and the charge for a LDCT is 10-20 times lower than for a PET scan. This underscores the recognition that LDCT is a very useful tool for identifying growth at a malignant rate prior to further invasive testing.

      The main point is that the definition of a “positive result” needs to be continually reevaluated and updated in light of emerging technology and evidence from ongoing screening programs with the goal of reducing unnecessary invasive procedures for non-malignant pulmonary NCNs, which will markedly reduce the concerns about potential harms and increase the benefit by early diagnosis and treatment of small, early curable lung cancers.

      References

      1. Henschke CI, Salvatore M, Cham M, Powell CA, DiFabrizio L, Flores R, et al. Baseline and annual repeat rounds of screening: implications for optimal regimens of screening. Eur Radiol. 2018; 28:1085-1094.

      2. Henschke CI, Yip R, Ma T, Aguayo SM, Zulueta J, Yankelevitz DF, for the I-ELCAP Investigators. CT screening for lung cancer: comparison of three baseline screening protocols. Eur Radiol 2018; 29:3321-3322.

      3. International Early Lung Cancer Action Program protocol. (2016) www.IELCAP.org/sites/default/files/I-ELCAP-protocol.pdf Accessed June 27, 2019

      4. American College of Radiology (ACR). Lung CT screening reporting & data system (Lung-RADS Version 1.0). https://www.acr.org/Quality-Safety/Resources/LungRADS

      5. Oudkerk M, Devaraj A, Vliegenthart R, Henzler T, Prosch H, Heussel CP, et al. European position statement on lung cancer screening. Lancet Oncology 2017; 18: e754-e766.

      6. Henschke CI, Yip R, Wolf A, Flores R, Liang M, Salvatore M, et al. CT screening for lung cancer: part-solid nodules in baseline and annual repeat rounds. AJR Am J Roentgenol 2016; 11:1-9.

      7. Radiologic Society of North America Quantitative Imaging Biomarkers Alliance (QIBA) Calculator. (2017) http://accumetra.com/solutions/qiba-lung-nodule-calculator. Accessed May 1, 2018.

      8. Li K, Yip R, Avila R, Henschke CI, Yankelevitz DF. Size and growth assessment of pulmonary nodules: consequence of the rounding. J Thorac Oncol 2016; 12: 657-62.

      9. Flores R, Bauer T, Aye R, et al. Balancing curability and unnecessary surgery in the context of computed tomography screening for lung cancer. J Thorac Cardiovasc Surg. 2014; 147:1619-26.

      10. American Association of Physicists in Medicine. AAPM Position Statement on Radiation Risks from Medical Imaging Procedures. https://www.aapm.org/org/policies/details.asp?id=406&type=PP Accessed June 27, 2019

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