SESSION TITLE: Lung Cancer Screening & Diagnosis Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM
PURPOSE: We sought to define the efficacy of CXR in the context of a cost-effectiveness analysis of LC screening comparing CT, CXR and no screening. CXR is considered ineffective because no RCT has shown a LC mortality reduction. However, CXR screening has been shown to produce a significant survival advantage in RCTs which is not attributable to overdiagnosis or other biases (JCO 20:1973-83;2002). The lung portion of PLCO compared CXR to no screening and reported no LC mortality benefit after 13 yrs follow-up (JAMA 306:1865-73;2011). Though the screening period was 3 yrs, the report included all LCs diagnosed over 13 yrs and did not report survival. Since CXR screening is unlikely to affect those diagnosed years after screening, and because sojourn time associated with CXR is estimated to be up to 4 yrs, we evaluated outcomes of LC diagnosed within 7 yrs of randomization.
METHODS: PLCO randomized 77,445 subjects to an experimental group (EG) undergoing a prevalence CXR and 3 annual incidence CXRs, and 77,456 others to an unscreened control group (CG). Using Kaplan-Meier methods and intent-to-screen analysis of PLCO data, LC survival and mortality were calculated for all LC patients diagnosed during the 13 yr follow-up as well as those diagnosed within 7 yrs of randomization. Incidence, mortality and stage distribution were compared with Fisher’s exact test. Survival was compared with the log-rank test. All p-values are two-sided.
RESULTS: After 13 yrs, 1838 and 1737 LCs were detected in EG and CG (RR=1.06; 95% CI 0.99-1.13; p=0.09). 5-yr survival was superior in EG (24% vs 19%; p<0.001). Conversely, LC mortality was slightly higher in EG (1217 vs 1203 LC deaths in EG vs CG; RR=1.012; CI 0.93-1.09; p=0.77). Within 7 yrs of randomization, 1072 and 1022 LCs were detected in EG and CG (RR=1.05; CI 0.96-1.14; p=0.27). 5-yr survival was 27% vs 18% in EG and CG (p<0.001). 764 and 811 patients died of LC in EG and CG (RR=0.94; 95%CI 0.85-1.04; p=0.24). There were significantly more Stage IA LCs in EG (RR 1.7; 95%CI 1.33 - 2.16; p<0.001). However, there were significantly fewer advanced Stage IIIB and IV LCs in EG (RR=0.87; 95%CI 0.76 - 0.99; p=0.04).
CONCLUSIONS: CXR screening was associated with a highly significant survival advantage not attributable to overdiagnosis and a significant reduction in the number of advanced cancers. Mortality analysis did not capture this benefit.
CLINICAL IMPLICATIONS: Annual CXR screening for LC is superior to no screening; its cost-effectiveness will be compared to CT using PLCO and NLST data.
DISCLOSURE: The following authors have nothing to disclose: John Paul Flores, Alejandro Moreno-Koehler, Matthew Finkelman, Jamie Caro, Gary Strauss
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