Developmental Therapeutics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD.
Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD.
Chest. 2018 Dec;154(6):1284-1290. doi: 10.1016/j.chest.2018.07.029. Epub 2018 Aug 3.
Previous studies with a limited number of patients have reported divergent findings on whether screening can detect small cell lung cancer (SCLC) at an earlier stage and whether there might be a survival benefit.
This study examined the characteristics of SCLC detected by using low-dose CT (LDCT) screening in the National Lung Screening Trial, a randomized study of individuals at high risk for developing lung cancer comparing LDCT imaging vs chest radiography. SCLC was denoted as screen detected if diagnosed ≤ 1 year of a positive screen or after a longer period but with no time gap between diagnostic procedures of > 1 year; interval detected if diagnosed ≤ 1 year of a negative screen; and nonscreen detected if the subject did not receive any screens or otherwise as postscreening.
A total of 143 cases of SCLC were diagnosed, including 49 (34.2%) screen detected, 15 (10.5%) interval detected, and 79 (55.2%) nonscreened/postscreening. Of the screening phase-diagnosed cases (ie, screen or interval detected), a higher proportion of SCLC cases compared with NSCLC cases were interval detected (23% vs 5%; P < .0001). A higher proportion of all SCLC cases compared with NSCLC cases were advanced stage (III/IV: 86% vs 36%; P < .0001). The unfavorable SCLC stage distribution extended across screen-detected (80% stage III/IV), interval-detected (86%), and nonscreened/postscreening (90%) cancers. Among screen-detected SCLC, only 63.3% had ≥ 1 noncalcified nodule in the cancer lobe compared with 85.4% of NSCLC cases (P < .0001). Even with very small LDCT screen-detected nodules, a high proportion of SCLC cases were late stage. There was no significant difference in survival between screen- and interval-detected or postscreening SCLC.
"Early detection" with the use of LDCT imaging had no impact on SCLC outcomes. A successful screening modality should ideally detect SCLC earlier than when it can be detected on LDCT scans.
此前一些针对少量患者开展的研究报告称，筛查能否更早发现小细胞肺癌（SCLC）以及是否可能带来生存获益，结果不一。
本研究通过国家肺癌筛查试验（National Lung Screening Trial）中使用低剂量 CT（LDCT）筛查发现的 SCLC 特征进行了研究。该试验为一项随机研究，比较了 LDCT 成像与胸部 X 线摄影对高危肺癌患者的效果。如果在阳性筛查结果后 1 年内确诊，或在更久后确诊但两次诊断之间无间隔超过 1 年，则将 SCLC 定义为筛查发现；如果在阴性筛查结果后 1 年内确诊，则将 SCLC 定义为间隔发现；如果患者未接受任何筛查或在筛查后被诊断，则将 SCLC 定义为未筛查/筛查后发现。
共诊断出 143 例 SCLC，其中 49 例（34.2%）为筛查发现，15 例（10.5%）为间隔发现，79 例（55.2%）为未筛查/筛查后发现。与非小细胞肺癌（NSCLC）病例相比，筛查期诊断的 SCLC 病例中，间隔发现的比例更高（23%比 5%；P<.0001）。所有 SCLC 病例中，与 NSCLC 病例相比，晚期病例比例更高（III/IV 期：86%比 36%；P<.0001）。不利的 SCLC 分期分布延伸至筛查发现（80%为 III/IV 期）、间隔发现（86%）和未筛查/筛查后发现（90%）的癌症中。在筛查发现的 SCLC 中，仅有 63.3%的癌症叶中存在≥1 个非钙化结节，而 NSCLC 病例中这一比例为 85.4%（P<.0001）。即使 LDCT 筛查发现的结节非常小，SCLC 病例仍有很高的晚期比例。筛查发现和间隔发现或筛查后发现的 SCLC 之间的生存无显著差异。
使用 LDCT 成像的“早期检测”对 SCLC 结局没有影响。理想情况下，有效的筛查方式应能更早发现 SCLC，而不是只能在 LDCT 扫描中发现。
