The impact of synchronous malignancies on survival in patients with early stage curable non-small-cell lung cancer

BACKGROUND: To determine if synchronous extrapulmonary malignancies in early stage lung cancer impact survival and cost of care in the current era of improved therapies and diagnostics. METHODS: Patients with stage I and II lung cancer were identified from the Ontario Cancer Registry and prognostic factors were obtained from provincial health administrative databases. Synchronous extrapulmonary malignancies were defined as those detected within 6 months from diagnosis of the lung primary. Survival was calculated using the Kaplan-Meier method and examined based on a 6-month landmark time point. The log-rank test and Cox proportional hazards regression was used to examine the effect of synchronous primaries on survival, univariately and after adjusting for prognostic factors. Cost of care was calculated by summing fees for all provincially funded services over 3 years. RESULTS: In a cohort of 6890 patients, those with synchronous malignancy had a HR of 1.32 (p = 0.026) for death in stage I patients, adjusted for other factors, while no association was found for stage II patients (HR=1.00, p = 0.99). 18F-FDG-PET/CT up to 6 months prior to lung cancer diagnosis had a HR of 0.84 (p = 0.003) for death adjusted for other factors. 3-year costs of care for these patients were $79,540 versus $54,520 in those without a synchronous malignancy (p<0.001). CONCLUSION: Extrapulmonary malignancies in stage I lung cancer patients may negatively impact survival with no such association for stage II patients. 18F-FDG-PET/CT performed before lung cancer diagnosis is associated with better survival. Cost of care is higher in patients with synchronous malignancies.