Lung Cancer

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TU_31_3627 - The Impact of Pathologic Staging of the Hilar/Mediastinal Nodes on Outcomes in Patients with Early-Stage NSCLC receiving Stereotactic Body Radiation Therapy

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

The Impact of Pathologic Staging of the Hilar/Mediastinal Nodes on Outcomes in Patients with Early-Stage NSCLC receiving Stereotactic Body Radiation Therapy
B. Mullins1, J. A. Holmes1, M. Rivera2, L. B. Marks3, J. Akulian2, A. Belanger2, and A. A. Weiner1; 1University of North Carolina Hospitals, Chapel Hill, NC, 2UNC Hospital, Chapel HIll, NC, 3Lineberger Comprehensive Cancer Center, University of North Carolina Hospitals, Chapel Hill, NC

Purpose/Objective(s): The role of invasive hilar/mediastinal nodal staging in early-stage non-small cell lung cancer (NSCLC) in the PET-CT era is unclear. We herein compare the outcomes in patients with early-stage NSCLC undergoing stereotactic body radiotherapy (SBRT), comparing groups based on the use of invasive hilar/mediastinal nodal staging.

Materials/Methods: The records of all consecutive patients undergoing SBRT for early-stage NSCLC between 2010 and 2017 were retrospectively analyzed. Some patients had navigational bronchoscopy (with endobronchial ultrasound-guided nodal biopsies) while others had CT-guided percutaneous biopsies (without any nodal sampling). Tumor size, location, histology, prior lung cancer history, radiation dose and receipt of pathologic staging of the hilar/mediastinal nodes were evaluated in correlation with nodal failure. Comparisons of continuous variables were performed using Wilcoxon rank sum and categorical variables were compared with Fisher’s exact test. Overall survival was estimated using the Kaplan Meier method.

Results: Overall, 158 patients (179 lesions) were treated with SBRT at a total prescribed dose of 32-60 Gy over 1-5 fractions. Median follow-up was 25 months. 149 patients (94%) underwent PET-CT staging prior to SBRT, and all patients underwent attempted biopsy with fiducial marker placement. Eighty-seven lesions (49%) were biopsied with CT-guidance and 92 lesions (51%) were biopsied using bronchoscopy. 26% of the biopsies were nondiagnostic of malignancy. Peripheral lesions were more frequently biopsied with CT-guidance than central lesions (p=0.007). All patients undergoing bronchoscopic biopsy had sampling of mediastinal and hilar lymph nodes, while nodal assessment of patients undergoing CT-guided biopsy was limited to PET/CT. The rate of nodal failure following SBRT was higher in patients who underwent CT-guided biopsy without pathologic staging of the nodes compared to those with bronchoscopic biopsy and pathologic staging of the nodes (28% vs. 11%, respectively, p=0.007). Nodal failure only (without distant metastasis or local failure) occurred in 16% and 7% of patients, respectively. No other patient, tumor, or treatment-related factors were associated with risk of nodal failure. Worse overall survival was observed after a nodal failure (median overall survival of 53 months without nodal failure vs 32 months with nodal failure, p=0.0006).

Conclusion: CT-guided biopsy without pathologic staging of the nodes was associated with increased nodal failure after SBRT in comparison to bronchoscopic biopsy with pathologic staging of the nodes. This data from a modern cohort of patients can help inform decision making on the importance of nodal sampling. Further work will involve radiographic characterization of the lesions and re-evaluation of pre-treatment PET-CT to guide future decision-making for pathologic staging prior to SBRT.

Author Disclosure: B. Mullins: None. J.A. Holmes: None. M. Rivera: None.

Brandon Mullins, MD, MS

University of North Carolina Hospitals

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