Department of Radiology, Clinical Operations and Cancer Services, Wake Forest Baptist Health and School of Medicine, Winston-Salem, North Carolina.
Wake Forest University Health Sciences Center, Winston-Salem, North Carolina.
J Thorac Oncol. 2019 Sep;14(9):1538-1546. doi: 10.1016/j.jtho.2019.05.045. Epub 2019 Jul 8.
In the National Lung Screening Trial (NLST) all cases with a 4-mm nodule (micronodule) and no other findings were classified as a negative study. The prevalence and malignant potential of micronodules in the NLST is evaluated to understand if this classification was appropriate.
In the NLST a total of 53,452 participants were enrolled with 26,722 undergoing low-dose computed tomography (CT) screening. To determine whether a micronodule developed into a lung cancer, a list from the NLST database of those participants who developed lung cancer and had a micronodule recorded was selected. The CT images of this subset were reviewed by experienced, fellowship-trained thoracic radiologists (R.F.M., C.C., P.M.B., and D.R.A.), all of whom participated as readers in the NLST.
There were 26,722 participants who underwent CT in the NLST, of which 11,326 (42%) participants had at least one CT with a micronodule. Five thousand five hundred sixty (49%) of these participants had at least one positive CT examination, of which 409 (3.6%) subsequently were diagnosed with lung cancer. Of the 409 lung cancer cases with a micronodule recorded, there were 13 cases in which a micronodule developed into lung cancer. Considering the 13 cases, they represent 1.2% (13 of 1089) of the lung cancers diagnosed in the CT arm of the NLST and 0.11% (13 of 11,326) of the total micronodule cases. Additionally they represent 0.23% (13 of 5560) of the micronodule and at least one positive CT examination cases and 3.2% (13 of 409) of the micronodule cases diagnosed with lung cancer. The average size of the nodule at baseline (recorded as maximum diameter by perpendicular diameter) was 3.0 × 2.5 mm (ranges 2 x 4 mm and 2 x 4 mm) and at the positive CT the nodule was 11.1 × 8.6 mm (ranges, 6 x 20 mm and 5 x 14 mm); a difference of average change in size of 8.1 × 6.1 mm. The average number of days from first CT with a micronodule recorded to positive CT was 459 days (range, 338 - 723 days), the mean time from first CT with micronodule to lung cancer diagnosis was 617 days (range, 380 - 1140 days) and the mean time from positive CT to lung cancer diagnosis was 160 days (range, 18 - 417 days). Histologically, there was one small cell carcinoma and 12 non-small cell with stages of IA in 8 (62%), stage IB in 2 (15%), and 1 each stage IIIA, IIIB, and IV. The overall survival of NSCLC cases with a micronodule was not significantly different than the survival of the CT subset diagnosed with NSCL (p = 0.36).
Micronodules are common among lung cancer-screened participants and are capable of developing into lung cancer; however, following micronodules by annual CT screening surveillance is appropriate and does not impact overall survival or outcome.
在国家肺癌筛查试验（NLST）中，所有 4 毫米结节（微结节）且无其他发现的病例均被归类为阴性研究。评估 NLST 中微结节的患病率和恶性潜能，以了解这种分类是否合适。
NLST 共纳入 53452 名参与者，其中 26722 名参与者接受低剂量计算机断层扫描（CT）筛查。为了确定微结节是否发展为肺癌，从 NLST 数据库中选择了一组参与者的名单，这些参与者患有肺癌且记录有微结节。该亚组的 CT 图像由经验丰富、接受过 fellowship 培训的胸部放射科医生（R.F.M.、C.C.、P.M.B.和 D.R.A.）进行审查，他们均作为 NLST 的读者参与。
NLST 中有 26722 名参与者接受了 CT 检查，其中 11326（42%）名参与者至少有一次 CT 显示微结节。这些参与者中有 5560（49%）名至少有一次 CT 检查呈阳性，其中 409 名（3.6%）随后被诊断为肺癌。在记录有微结节的 409 例肺癌病例中，有 13 例微结节发展为肺癌。考虑到这 13 例病例，它们占 NLST CT 组诊断的肺癌的 1.2%（13/1089），占微结节总病例的 0.11%（13/11326）。此外，它们占微结节和至少一次阳性 CT 检查病例的 0.23%（13/5560）和微结节诊断为肺癌的 3.2%（13/409）。基线时结节的平均大小（以垂直直径记录为最大直径）为 3.0×2.5 毫米（范围 2 x 4 毫米和 2 x 4 毫米），在阳性 CT 时结节为 11.1×8.6 毫米（范围 6 x 20 毫米和 5 x 14 毫米）；平均大小变化为 8.1×6.1 毫米。从首次记录有微结节的 CT 到阳性 CT 的平均天数为 459 天（范围 338-723 天），从首次有微结节的 CT 到肺癌诊断的平均时间为 617 天（范围 380-1140 天），从阳性 CT 到肺癌诊断的平均时间为 160 天（范围 18-417 天）。组织学上，有 1 例小细胞癌和 12 例非小细胞癌，其中 8 例（62%）为 IA 期，2 例（15%）为 IB 期，1 例为 IIIA 期，1 例为 IIIB 期，1 例为 IV 期。有微结节的 NSCLC 病例的总生存率与 CT 组诊断的 NSCLC 病例的生存率无显著差异（p=0.36）。
微结节在肺癌筛查参与者中很常见，并且能够发展为肺癌；然而，通过每年 CT 筛查监测微结节是合适的，不会影响总体生存率或结果。
