Distant Metastasis-Free Survival by Smoking History, 0 versus >0 Pack Years Smoking history (pack-years) No. of Subject Event Censored Median Survival (95% CI) 1 Yr Survival 2 Yr Survival 3 Yr Survival 4 Yr Survival 5 Yr Survival 0 174 11 (6%) 163 (94%) NA (NA, NA) 98.2% (94.6%, 99.4%) 96.4% (92.1%, 98.3%) 94.5% (89.6%, 97.1%) 93.8% (88.7%, 96.6%) 93.8% (88.7%, 96.6%) >0 373 74 (20%) 299 (80%) NA (NA, NA) 89.1% (85.4%, 92.0%) 81.2% (76.6%, 85.0%) 80.5% (75.9%, 84.4%) 78.5% (73.6%, 82.6%) 77.4% (72.3%, 81.7%)