Survival Following Detection of Stage I Lung Cancer by Screening in the National Lung Screening Trial

Background: There is limited information about survival of stage I lung cancer diagnosed by screening.

Research question: What was the survival rate of screen-detected stage I lung cancer in the National Lung Screening Trial (NLST), and was it affected by screening method, patient or tumor characteristics, or treatment method?

Study design and methods: The study cohort consisted of all NLST participants with screen-detected stage I lung cancer. Lung cancer-specific survival for stage I overall and for IA and IB substages were compared in the low-dose CT and chest radiography (CXR) screening randomization arms and with an analogous cohort from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute; the cumulative incidence competing risk method was used for analysis. Cox proportional hazards models were used to evaluate the association between lung cancer-specific survival and screening arm, patient factors, primary tumor size, and treatment.

Results: There were 324 screen-detected stage I lung cancers in the low-dose CT arm and 125 in the CXR arm. The 10-year survival in the low-dose CT arm was greater than in the CXR arm (73.4% vs 64.6%; P = .05), and both were greater than in the Surveillance, Epidemiology, and End Results cohort (55.6%; P < .001 vs low-dose CT arm, P = .04 vs CXR arm). Proportional hazards models revealed a greater likelihood of survival in the low-dose CT arm (hazard ratio [HR], 0.69; 95% CI, 0.5-0.98) and with primary tumor size below the median of 17 mm (HR, 0.61; 95% CI, 0.42-0.88). There was no survival difference between treatment with limited resection vs full resection (HR, 1.11; 95% CI, 0.6-1.9), whereas nonsurgical treatment was associated with a reduced likelihood of survival compared with full resection (HR, 3.1; 95% CI, 1.6-6.0).

Interpretation: Long-term lung cancer-specific survival of stage I lung cancer was greater with low-dose CT imaging than with CXR screening or in the general population, for smaller primary tumor size, and with surgical treatment.