2472 - Safety and Efficacy of Lung Stereotactic Body Radiation Therapy for Surgical Staple Line Recurrences

Purpose/Objective(s): Surgical resection remains the gold standard for stage I non-small cell lung cancer (NSCLC) and for diagnostic and therapeutic management of solitary metastases. A gold standard has not yet been established, however, for local recurrences (LR) of the lung along surgical staple lines. We have updated our initial report on the safety and efficacy of lung SBRT as a single modality salvage treatment strategy for staple line recurrences following surgical resection.

Materials/Methods: We identified 23 patients from an IRB-approved prospectively maintained database who were treated for staple line recurrences after surgical resection for the management of stage I NSCLC or oligometastasis. These patients were treated from 5/2012 to 7/2022. Seventeen patients had primary NSCLC and six patients had oligometastases. We calculated the median time from surgery to SBRT treatment, median follow up (MFU), and crude rates of local (defined as in-field and along the staple line), regional (defined as out-of-field lobe/lung and/or regional lymph nodes), and distant (contralateral thorax or distant systemic spread) control. Common terminology criteria for adverse events version 4 (CTCAEv4) were used to measure treatment-related toxicities.

Results: Median age at the time of treatment was 68 years (range 45-86 years). The median time from LR to initiation of SBRT was 28 months (range 3-150 months). The median total SBRT dose was 50 Gy (range 35.0-60.0 Gy) with median dose per fraction of 10 Gy (range 4.5-18.0 Gy). A simultaneous integrated boost (SIB) technique, which included the entire staple line with a tumor boost, was employed in 4/23 (17%) cases. With MFU of 30 months (range 2-71 months) three patients experienced a local failure at the staple line, for a crude local control rate of 87%. Eight patients failed regionally (in the lung, outside of the SBRT field) and eight patients failed distantly (35%). Two patients had local, regional, and distal progression on follow up (9%). All toxicities reported were grade 1 (fatigue (1), dyspnea (1), pneumonitis (2), and chest wall pain (1)).

Conclusion: Salvage SBRT for surgical staple line failures appears to be efficacious and very well tolerated (no grade 2 or above toxicities). Further investigation is needed to determine the optimal dose and treatment volume for this unique, but growing cohort of patients.