Post-Treatment Imaging in Lung Cancer Patients: Adherence to Surveillance Guidelines Is Associated with Improved Survival in a Longitudinal Cohort.
OBJECTIVE Surveillance imaging for non-small cell lung cancer (NSCLC) survivors may reduce mortality from recurrence and secondary primary tumors, but survival impact is difficult to assess due to confounding from symptom-driven imaging. We evaluated the association between active surveillance adherence (ASA) and survival in a longitudinal cohort. METHODS Patients with Stage I-III NSCLC who received curative-intent therapy and survived >6 months were identified within the Veterans Health Administration (2008-2016). Active surveillance adherence (ASA) was defined using contemporaneous NCCN guidelines and clinical chart abstraction. Time-to-event analysis incorporated time-varying ASA exposure, modeled as a continuous variable and as a percentage of time elapsed, with adjustment for clinical characteristics. Subgroup analysis was performed among patients with recurrence. Time to recurrence and post-recurrence survival were compared to evaluate potential lead-time bias. RESULTS The cohort included 5650 patients; predominantly White (73%), male (97%) with Stage I disease (54%) treated with Surgery alone (52%). ASA was associated with a reduced risk of death, (HR 0.92 per 6 months [95%CI 0.89-0.95, p<0.001]). Symptom- driven imaging was not associated with reduced risk of death (HR 1.05 per 6 months [1.00 -1.11, p=0.066]). In patients with recurrence (N=2199) median overall survival from treatment was 34 months [33, 36] for surveillance-detected vs 27 months [24, 30] for symptom-detected, p<0.0001. Time to recurrence did not differ significantly. CONCLUSIONS ASA was associated with significant survival benefit compared to symptom-driven imaging which is not explained by lead-time bias, contrasting with prior reports failing to demonstrate benefits of surveillance following treatment for lung cancer.