Outcomes of invasive mediastinal nodal staging versus positron emission tomography staging alone for early-stage non-small cell lung cancer treated with stereotactic body radiation therapy

Background: The benefit of invasive mediastinal nodal staging (IMNS) in addition to positron emission tomography-computed tomography (PET/CT) is undefined for early stage non-small cell lung cancer (NSCLC). This multi-institutional investigation aimed to evaluate outcomes and patterns of failure in patients staged with PET/CT with or without additional IMNS. Methods: Two academic centers assessed all consecutive patients staged with PET/CT for early-stage, primary lung NSCLC (cT1-2aNOMO) treated with SBRT. Local recurrence-free survival (LRFS), nodal recurrence-free survival (NRFS), distant metastasis-free survival (DMFS), and overall survival (OS) were calculated using Kaplan-Meier methodology. Univariate and multivariate Cox proportional hazards modeling addressed factors associated with outcomes. Results: Overall, 180 patients (199 lesions) were staged with PET/CT alone and 56 patients (58 lesions) underwent additional IMNS. Among patients receiving IMNS, 52 (93%) underwent EBUS and 4 (7%) underwent mediastinoscopy. At a median follow-up of 33.5 months (range, 1.9-80.9 months), there was no significant difference in LRFS (37 vs. 47 months, p = 0.309), NRFS (34 vs. 42 months p = 0.370), DMFS (36 vs. 47 months, p = 0.234) or OS (37 vs. 47 months, p = 0.236) between patients undergoing PET/CT-only versus PET/ CT + IMNS staging, respectively. Receipt of IMNS did not correlate with any outcome on either univariate or multivariate analysis (p > 0.05). Patterns of failure in both groups were similar, including crude isolated nodal failure rates (8% PET/CT-only versus 14% PET + IMNS group, p = 0.202). Conclusions: Patients undergoing IMNS had similar survival and patterns of recurrence as those receiving PET/ CT alone. Further study, ideally prospectively, is needed to determine which subgroups might benefit from IMNS.