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ORAL 25 - Biology and Other Issues in SCLC (ID 125)
- Event: WCLC 2015
- Type: Oral Session
- Track: Small Cell Lung Cancer
- Presentations: 1
ORAL25.01 - Screening for Small Cell Lung Cancer: Analysis of the National Lung Cancer Screening Trial Data (ID 2145)
10:45 - 12:15 | Author(s): P. Pinsky
Given its widely metastatic nature at the time of diagnosis and the lack of effective therapies, early detection could theoretically have a beneficial impact on small cell lung cancer (SCLC) patient survival. However in the National Lung Screening Trial (NLST), there was no survival advantage for SCLC in the low dose computed tomography (LDCT) arm versus the chest radiography (CXR) arm. We investigated whether LDCT could detect SCLC and whether such screen detection offered a stage and/or survival benefit.
Subjects randomized to the LDCT arm in NLST received three annual LDCT screens. Incident cancers were tracked with annual surveys and confirmed with medical records, with abstractors coding lung cancer stage and histology. “Best” stage was defined as pathologic stage if available, otherwise clinical stage. Deaths were tracked with the annual surveys and supplemented by the National Death Index. Cancer was denoted as screen-detected if it was diagnosed within one year of a positive screen or if it was diagnosed after a longer period but with no time gap between diagnostic procedures of more than one year. An interval cancer was defined as a cancer diagnosed within one year of a negative screen. Non-screen detected or interval cancers were denoted as non-screened if the subject did not receive any NLST screens or otherwise as post-screening.
26,722 subjects were randomized to the LDCT arm (median follow up 6.5 years; 59% men; median age at enrollment 62). 143 SCLCs were diagnosed [49 (34.2%) screen-detected, 15 (10.5%) interval, 79 (55.2%) non-screened/ post-screening]. The ratio of interval to screen detected cases was significantly higher for SCLC (15/49=0.31) than for NSCLC (29/591=0.05); p < 0.0001. 123 of 143 (86%) SCLCs were detected at late-stages (best stage III/IV); the unfavorable stage-distribution persisted among screen-detected, interval and non-screened/ post-screening cases with only 15 (10.5%) detected in early-stages. Three-year lung cancer-specific survival was 72% for early-stage versus 11% for late-stage disease. There was no significant difference in five-year survival between screen-detected, interval and non-screened/post-screening SCLCs (15.3%, 20.0% and 13.8%, respectively). Unlike NSCLC, even at small nodule sizes the proportion of screen-detected SCLCs that were late stage was very high.
Analysis of SCLC detected in the NLST LDCT arm show that yearly LDCT screens do not detect a significant number of early stage SCLCs. Compared with NSCLC, a higher proportion of SCLCs are interval-detected than screen-detected. Further, there is no stage-shift or survival benefit for screen- detected SCLCs compared with interval or post-screen detected cases. To our knowledge this is the largest analysis to date of SCLC detected in a screening study. Our results indicate that in order for a screening modality to be successful for SCLC, it is necessary (but not sufficient) to be able to detect it earlier than does LDCT.
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