Target volume definition for staple line recurrences of non-small cell lung cancer

Background: Staple line (SL) recurrences of non-small cell lung cancer (NSCLC) are commonly treated with radiotherapy (RT), but the target volume definition — whole SL versus focused on recurrence — is unclear. The aim of the study was to determine the appropriate target volume for RT of SL recurrences. Materials and methods: Twenty-two consecutive patients (20 stage I, 2 stage II) treated with salvage RT for SL recurrences were retrospectively analyzed. Imaging features at the time of SL recurrence were evaluated to guide target volume definition. Results: Surgery : All patients had complete tumor resection (wedge resection in 10 (45%) and lobectomy in 12 (55%) patients). 14 (64%) patients had risk factors for recurrence, including surgical margins ≤ 2 cm, angiolymphatic and visceral pleural invasion.  Salvage RT : After a median 26 months (9–67), all 22 patients developed SL recurrence which was metabolically active on PET in all and biopsy-confirmed in 18/22 (82%) patients. All patients underwent RT targeting the location of the SL recurrence only. 13/22 (59%) patients had additional PET-negative nodular or linear SL changes that were not included in the irradiated volume. Recurrence after RT : After a median 17 months (9–34) 10/22 (45%) patients recurred either regionally 6/10 (60%), in the lungs 4/10 (40%) or distally 3/10 (30%). No patient recurred at the SL. Two-year overall and disease-free survival rates after RT were 71% and 65%, respectively.  Conclusion: RT to SL recurrences alone results in excellent local control. Additional treatment to reduce regional and distant recurrences should be considered.