Lung SBRT Outcomes for Inoperable Early-Stage Lung Cancer Are Impaired in Patients With Solid Organ Transplants.

[PURPOSE] To characterize outcomes for solid organ transplant patients with medically inoperable early-stage lung cancer (ES-LC) treated with lung stereotactic body radiotherapy (SBRT).

[METHODS] We surveyed our institutional review board-approved prospective lung SBRT data registry from 2003 to 2023 for any transplant patients. Patterns of failure were assessed, as well as overall survival (OS) and disease-free survival (DFS). Univariate prognostic factors for OS and DFS were identified with Cox proportional hazards regression.

[RESULTS] Twenty-eight of 1976 definitively treated patients (1.4%) met study criteria. Median follow up was 12.4 months. Patient characteristics included: male (67.9%), median pack-years smoking of 34; median age 70.0 years; median Karnofsky Performance Status (KPS) 80. Organs transplanted were lung (57.2%), liver (21.4%), heart (21.4%). Tumor characteristics included: median size 2.4 cm; 85.7% with biopsy-proven cancer. Toxicity (any grade/type) was reported in 9 (32.1%) patients. Failure patterns were local 21.4%, lobar 7.1%, nodal 10.7% and distant 32.1%. First site of failure was distant in 50.0% patients. Median DFS and OS were 17.1 and 14.5 months, respectively. Increasing pack-years smoking was the only factor associated with increased disease failure on univariate analysis (UVA) (P = .0016). KPS and tumor size were significantly associated with OS on UVA and on multivariable analysis (P = .0075) and (P = .0181), respectively.

[CONCLUSIONS] Organ transplant patients with inoperable ES-LC had higher than expected rates of local failure, decreased cancer control and poorer overall survival after SBRT. We hypothesize that transplant-associated immunosuppression promotes metastatic progression and a tumor biology resistant to SBRT.