Clinical and economic outcomes associated with lymph node examination status in early-stage non-small cell lung cancer: a real-world US study using the SEER-Medicare linked database.

BACKGROUND

Clinical practice guidelines recommend adjuvant therapy for patients with early non-small cell lung cancer (eNSCLC), especially those with lymph node metastasis. This study evaluated the prevalence of lymph node examination and its association with adjuvant treatment rates, overall survival (OS), and healthcare costs among United States (US) Medicare patients with resected eNSCLC.

METHODS

This retrospective observational cohort study used Surveillance, Epidemiology, and End Results cancer registry data linked with Medicare claims data. Eligible patients were aged ≥65 years with newly diagnosed non-small cell lung cancer (NSCLC) stages IA to IIIB [the , 7th edition] between January 2010 and December 2017 with surgery ≤1 month prior to or ≤12 months after diagnosis. Patients were grouped by lymph node examination status: no examination (pNX), examination and no metastasis (pN0), or metastasis staging in N1 (pN1) or N2 (pN2). OS and costs were evaluated by examination status and number of lymph node examined. OS was analyzed using extended Cox proportional hazards models for specific time periods and time interaction with examination status, and adjusted for patient characteristics. Adjusted post-surgical healthcare costs per patient per month (PPPM) were analyzed using gamma-log regression models.

RESULTS

Among the 14,648 patients included in the study, approximately 11% were pNX, whereas most were pN0 (68%), followed by pN1 (11%) and pN2 (10%). Adjuvant treatment rates were higher for pNX (35%) than pN0 (18%), but lower than pN1 (68%) and pN2 (74%) patients (P<0.001). Unadjusted OS for pNX patients was nearly identical to pN2, and significantly worse compared to pN0 and pN1 (P<0.0001). After adjusting for patient characteristics, pNX patients had higher risk of death relative to pN0 patients (P<0.001). Marginal mean adjusted total costs were comparable across pNX ($15,827 PPPM), pN0 ($12,712 PPPM) and pN1 ($17,089 PPPM), but significantly less for pN0 compared to pN2 ($23,566 PPPM) (P=0.002).

CONCLUSIONS

Inadequate lymph node examination is associated with underutilization of adjuvant treatment and poor OS in resected NSCLC. In the current era of targeted and immunotherapies, lymph node examination is more important than ever, implicating the need for Quality Improvement practices and multidisciplinary coordination.