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R. Kakinuma



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    P1.20 - Poster Session 1 - Early Detection and Screening (ID 172)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P1.20-003 - Lung Cancers Detected Using Low-dose CT Screening: Results of an Eight-year Observational Study (ID 1779)

      09:30 - 16:30  |  Author(s): R. Kakinuma

      • Abstract

      Background
      To evaluate lung cancers detected using low-dose CT screening between February 2004 and March 2012.

      Methods
      The number of screenees analyzed in the observational study was 12,116. Screenees were classified into three groups based on their smoking index (SI): SI ≥ 600, SI < 600, and never-smokers. Overall, 147 lung cancers in 132 cases treated at the National Cancer Center Hospital and the National Cancer Center Hospital East were evaluated according to the smoking index. Adenocarcinomas were evaluated based on the following classification: group A (adenocarcinoma in situ and minimally invasive adenocarcinoma), and group B (invasive adenocarcinoma). Statistical analyses were performed using the chi-square test.

      Results
      The ages of the patients with lung cancer ranged between 42 and 85 years (mean, 61 years). Thirty-two of the 2989 male screenees (1.48%) and 2 of the 149 female screenees (1.34%) in the SI≥600 group, 22 of the 2989 male screenees (0.74%) and 10 of the 796 female screenees (1.26%) in the SI<600 group, and 16 of the 2148 male screenees (0.74%) and 50 of the 3878 female screenees (1.29%) in the never-smoker group were diagnosed as having lung cancer. Among the 147 lung cancers, 8 lesions (5.4%) did not present as nodules and instead appeared as a partial thickening of the bulla wall, a funicular-like shadow, a pneumonia-like shadow, etc. Among the remaining 139 lung cancers, 35 lesions (25.2%) presented as pure ground-glass nodules (GGNs), 64 lesions (46%) presented as part-solid nodules, and 40 lesions (28.8%) presented as solid nodules. The histology of the lung cancers was adenocarcinoma in 132 cases (89.8%), squamous cell carcinoma in 8 cases (5.4%), small cell carcinoma in 3 cases (2%), adenosquamous carcinoma in 1 case (0.7%), carcinoid tumor in 2 cases (1.4%), and NSCLC in 1 case (0.7%). The disease stages were as follows: IA, 127 (86.4%); IB, 11 (7.5%); IIA, 2 (1.4%); IIB, 1 (0.7%); IIIA, 3 (2.0%); and IIB, 3 (2.0%). Among the 147 cancers, the number of incident cases was 8 in the SI≥600 group (median follow-up period, 3.1 years), 3 in the SI<600 group (median follow-up period, 2.9 years), and none in the never-smoker group (median follow-up period, 3.0 years). Lung cancer cases in smokers (including ex-smokers) occurred predominantly in men (male, 54; female, 12), while lung cancer cases in never-smokers occurred predominantly in women (female, 50; male, 16) (P < 0.0001). The number of adenocarcinomas in smokers (including ex-smokers) was 29 in group A and 24 in group B, while the number of adenocarcinomas in never-smokers was 42 in group A and 23 in group B (P = 0.274). In the never-smoker group, the number of adenocarcinomas in men was 7 in group A and 9 in group B, while the number of adenocarcinomas in women was 35 in group A and 14 in group B (P < 0.05).

      Conclusion
      The number of invasive adenocarcinomas was not statistically different between smokers (including ex-smokers) and never-smokers. Never-smokers should also be a target population of CT lung cancer screening. Adenocarcinoma may be overdiagnosed among female never-smokers.

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    P2.20 - Poster Session 2 - Early Detection and Screening (ID 173)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P2.20-005 - Volume Doubling Times of Subsolid Nodules Detected Using Low-dose CT Lung Cancer Screening based on an Eight-year Prospective Observation (ID 1798)

      09:30 - 16:30  |  Author(s): R. Kakinuma

      • Abstract

      Background
      To evaluate the volume doubling times (VDTs) of subsolid nodules (SNs) detected using low-dose CT lung cancer screening.

      Methods
      Patients with SNs detected between February 2004 and January 2005 were enrolled. Among the SNs that were detected after February 2005, increasing SNs and resected SNs after follow-up were also included in this study. After confirming the persistency of the SNs at 3 months after screening, a follow-up thin-section CT examination was performed every year, in principle. Dedicated software was developed to analyze the SNs. The volumes of the subsolid nodules were calculated based on the summation of the area of each CT slice multiplied by the CT slice thickness (i.e., 1 mm). The area of a SN on each CT slice was determined semiautomatically. The measurement of each area was performed twice, and the average of the first and second measurements was used for the volume calculation. VDTs were calculated using the following formula; (T1-T0)*log2/log(V1/V0).

      Results
      As of June 14, 2013, the measurements of 81 SNs in 72 cases had been completed. The interim results were as follows. VDTs were classified into positive values (n = 56) and negative values (n = 25). VDTs with positive values ranged from 333 to 83384 days (median, 1981 days; VDT >4500 days, n = 13), while the VDTs with negative values ranged from -110007 to -1014 days (median, -13317 days; VDT <-4500 days, n = 20). The initial volumes for the positive VDTs ranged from 45 to 3486 mm[3 ](median, 199 mm[3]), while the initial volumes for the negative VDTs ranged from 45 to 1037 mm[3 ](median, 189 mm[3]); the difference in initial volume between the positive VDTs and the negative VDTs was not statistically significant (P = 0.468)[. ]Among the 72 cases, 9 SNs in 9 cases (12.5%) were resected and diagnosed as adenocarcinomas (adenocarcinoma in situ [AIS], n = 4; minimally invasive adenocarcinoma [MIA], n = 3; and invasive adenocarcinoma [IA], n = 2). The VDTs for AIS ranged between 726 and 1723 days (median, 1154 days), the VDTs for MIA ranged between 333 and 806 days (median, 536 days), and the VDTs for IA ranged between 348 and 448 days (median, 398 days). The measurements of other SNs are ongoing.

      Conclusion
      The interim results showed that adenocarcinomas with a higher degree of invasiveness had a shorter VDT. Tentatively assuming that absolute values of VDTs >4500 days indicate clinical stability in volume despite the inherent variability of semiautomatic volumetry, 40% of the SNs were stable after an eight-year observation period.