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J. Caro
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P3.06 - Poster Session/ Screening and Early Detection (ID 220)
- Event: WCLC 2015
- Type: Poster
- Track: Screening and Early Detection
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.06-003 - Effectiveness of Lung Cancer Screening Comparing Computed Tomography (CT) to Chest X-Ray (CXR) to No Screening in PLCO and NLST Randomized Trials (ID 725)
09:30 - 09:30 | Author(s): J. Caro
- Abstract
Background:
We sought to estimate the relative effectiveness of CT and CXR versus no screening in the context of a comparative cost-effectiveness analysis of lung cancer screening. CXR is considered ineffective because no randomized population trial (RPT) has shown a lung cancer mortality reduction. In the Mayo Lung Project, however, CXR screening produced a significant survival advantage which was not attributable to overdiagnosis or other screening biases (JCO 20:1973-83; 2002). The lung portion of the Prostate Lung Colon Ovary (PLCO) Cancer Screening Trial reported no lung cancer mortality reduction with CXR versus no screening, and it is considered to be a negative trial. The National Lung Screening Trial (NLST) was the first lung cancer screening RPT to report a mortality reduction comparing CT to CXR, but lacked an unscreened control. Survival from these trials has not been reported.
Methods:
To compare effectiveness of CXR and CT versus no screening, we calculated mortality, survival, and stage distribution in an intent-to screen analysis of PLCO and NLST data. Only lung cancers diagnosed within 7 years of randomization in PLCO were considered to match the median 6.7 years follow-up in NLST. Kaplan-Meier survival was compared by the log-rank test. Incidence, mortality, and stage distribution were compared with Fisher’s exact test. All p-values are two-sided.
Results:
In PLCO, 154,897 participants were randomized to either four annual CXRs over 3 years or to no screening. Within 7 years of randomization, 1072 and 1022 lung cancers were diagnosed, respectively (RR=1.05; 95%CI 0.96-1.14; p=0.271). 5-year survival was 27% and 18% (p<0.001). Mortality analysis revealed 764 and 811 lung cancer deaths in CXR and control groups (RR=0.94; 95%CI 0.85-1.04, p=0.244). The CXR group had significantly more stage IA cancers (RR 1.70; 95%CI 1.33 – 2.16; p<0.001) and fewer advanced stage IIIB and IV cancers (RR=0.87; 95%CI 0.76 – 0.99; p=0.044). NLST randomized 53,452 participants to either three annual CTs or CXRs over 2 years. There were 1089 and 969 lung cancers in the CT and CXR groups respectively (RR=1.12; 95%CI 1.03-1.22; p=0.007). 5-year survival was 49% and 33% (p<0.001). Mortality comparisons revealed 449 and 528 lung cancer deaths in the CT and CXR groups (RR=0.850; 95%CI 0.751-0.964, p=0.012). There were significantly more stage IA cancers (RR 2.16; 95%CI 1.82 – 2.56; p<0.001) and fewer advanced stage IIIB and IV cancers in the CT versus CXR groups (RR=0.74; 95%CI 0.63 – 0.87; p<0.001).
Conclusion:
Based upon similar lung cancer incidence, improved survival, and a more favorable stage distribution (particularly a reduction in the number of advanced cancers) in PLCO, CXR screening is superior to no screening, and overdiagnosis does not account for this advantage. While CXR screening is superior to no screening, CT is more efficacious than CXR in NLST. As CT is more expensive, has a higher false positive rate, and is more likely to detect overdiagnosed cancers than CXR, CXR may still be cost-effective compared to CT. Accordingly, a cost-effectiveness analysis employing NLST and PLCO data is ongoing.
