Chest
Volume 154, Issue 6, December 2018, Pages 1284-1290
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Original Research: Lung Cancer
Characteristics and Outcomes of Small Cell Lung Cancer Detected by CT Screening

Some of the findings of this study were presented at the International Association for the Study of Lung Cancer Annual Meeting, September 6-9, 2015, Denver, CO.
https://doi.org/10.1016/j.chest.2018.07.029Get rights and content

Background

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.

Methods

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.

Results

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.

Conclusions

“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.

Section snippets

Materials and Methods

The NLST was a randomized screening trial comparing LDCT vs CXR (Fig 1A).4, 5 Subjects were enrolled from August 2002 through April 2004 and were randomly assigned to undergo three annual screenings with either LDCT scanning or CXR. Screening occurred from August 2002 through September 2007. Eligible participants were 55 to 74 years of age, had a history of cigarette smoking of at least 30 pack-years, and, if former smokers, had quit within the previous 15 years. Individuals who had previously

Results

There were 26,722 subjects randomized to the LDCT imaging arm, and the median follow-up was 6.5 years (Fig 1A). A total of 59% were men, and the median age at enrollment was 62 years. A total of 143 SCLC cases and 926 NSCLC cases were detected in the LDCT arm.

Table 1 presents LDCT arm SCLC cases according to stage and mode of detection. Of 143 SCLC cases, 49 (34.2%) were screen-detected, 15 (10.5%) were interval-detected, and 79 were nonscreened or postscreening (55.2%) cancers. Of 64 interval-

Discussion

Data from the NLST were analyzed to assess the characteristics and outcomes of SCLC with a focus on LDCT-detected cases. Novel observations from this analysis are as follows: (1) compared with NSCLC, a significantly higher proportion of SCLC cases were interval cancers, diagnosed within 1 year following a negative screening, and only one third of cases were screen detected; (2) as expected, the majority of SCLC cases were late-stage cancers but, surprisingly, the unfavorable stage distribution

Conclusions

Analysis of SCLC diagnosed during LDCT screening in the NLST shows that yearly LDCT screens detected a significant number of SCLC cases. Compared with NSCLC cases, a higher proportion of SCLC cases were interval detected than screen detected. However, no stage shift or survival benefit for screen-detected SCLC cases compared with interval- or postscreen-detected cases was observed. Even for screen-detected SCLC for which the lesion observed on the LDCT screen was small, the proportion of

Acknowledgments

Author contributions: A. T., E. S., and P. Pinsky conceived and designed the analysis, collected the data, performed the analysis and wrote the paper. P. Pattanayak collected the data, performed the analysis and contributed to manuscript writing. All authors had full access to the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Financial/nonfinancial disclosures: None declared.

Role of sponsors: The funding agencies had no role in the

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Dr Pattanayak is currently at Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD.

FUNDING/SUPPORT: This work was supported in part by the Center for Cancer Research, National Cancer Institute at the National Institutes of Health [Grant ZIA BC 011793].

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