Stereotactic body radiotherapy for adrenal oligometastasis in lung cancer patients

Objective: To report our experience on stereotactic body radiotherapy (SBRT) in adrenal metastases from lung cancer. Methods: 37 oligometastatic lung cancer patients with 38 adrenal metastases submitted to SBRT were retrospectively analyzed. SBRT was delivered by volumetric modulated arc therapy (VMAT) or helical tomotherapy (HT). Primary study end point was local recurrence-free survival (LR-FS) and secondary end points were distant-progression free survival (d-PFS) and overall survival (OS). Results: Median age was 67 years and primary tumor was non-small-cell lung cancer in 27 (73%) and small-cell lung cancer in 10 (27%) patients. Adrenal metastases were in the left side in 66% cases. Median prescribed dose was 30 Gy in 5 fractions for a median biologically equivalent dose (alpha/beta ratio 10 Gy, BED10) of 48 Gy. Most patients (62%) were submitted to SBRT alone, while the others (38%) received chemo-, immune- or target- therapies. Median follow-up was 10.5 months, median OS 16 months and median d-PFS 3 months. 27 (70%) patients obtained a local control with a median LR-FS of 32 months. LR-FS was significantly related to BED10 with a better LC with BED10 >= 72 Gy, 1- and 2 year LR-FS rates were 54.1 +/- 11.6% and 45 +/- 12.7% vs 100 and 100% for BED <= 59.5 Gy and BED >= 72 Gy, respectively (p = 0.05). There was no severe toxicity. Conclusion: SBRT was effective and safe in lung cancer adrenal metastases. A dose-response relationship was found between BED10 >72 Gy and better local control. No significant toxicity was registered thanks to the respect of dose constraints and suspension of chemoand target-therapies. Advances in knowledge: SBRT with a BED10 >72 Gy is an effective treatment for adrenal oligometastatic lung cancer patients.