Novel Dose Escalation Approaches for Stereotactic Body Radiotherapy to Adrenal Oligometastases: A Single-Institution Experience.

OBJECTIVES: The role of local disease control in the oligometastatic setting is evolving. Stereotactic body radiation therapy (SBRT) is a noninvasive treatment option for oligometastases; however, using ablative radiation doses for adrenal metastases raises concern given the proximity to radiosensitive organs. Novel treatment techniques may allow for selective dose escalation to improve local control (LC) while minimizing dose to nearby critical structures. MATERIALS AND METHODS: We retrospectively reviewed patients with adrenal oligometastases treated with SBRT from 2013 to 2018. LC, disease-free survival, and overall survival were estimated using Kaplan-Meier methods. Predictors of outcomes were evaluated by log-rank and Cox proportional hazard analyses. RESULTS: We identified 45 adrenal oligometastases in 41 patients treated with SBRT. The median age at treatment was 67 years (range, 40 to 80). The most common primary histologies were non-small cell lung cancer (51%), renal cell carcinoma (24%), and small cell lung cancer (10%). The median prescription dose was 50 Gy (range, 25 to 60 Gy), with 30 (67%) lesions receiving ≥50 Gy and 14 (31%) receiving 60 Gy. In total, 26 (58%) lesions received a simultaneous-integrated boost. Of the 42 treatment simulations, 26 (62%) were supine, 5 (12%) prone, and 11 (26%) in the left lateral decubitus position. At a median follow-up of 10.5 months, there were 3 local failures with a 12-month LC rate of 96%. CONCLUSIONS: Adrenal SBRT for oligometastatic disease is a feasible, noninvasive option with excellent LC and minimal toxicity. Lesions in close proximity to radiosensitive organs may benefit from dynamic patient positioning and selective simultaneous-integrated boost techniques to allow for dose escalation, while also limiting toxicity risks.

Incidence, features and management of radionecrosis in melanoma patients treated with cerebral radiotherapy and anti-PD-1 antibodies.

BACKGROUND: Brain radiotherapy is used in the management of melanoma brain metastases (MBM) and can result in radionecrosis. Anti-PD-1 is active in the brain and may increase the risk of radionecrosis when combined with radiotherapy. We studied the incidence, associated factors and management of radionecrosis in longer-term survivors with MBM treated with this combination. METHODS: Patients with MBM treated with radiotherapy and anti-PD-1 who survived >1 year were identified to determine radionecrosis incidence (Cohort A, n = 135). Cohort A plus additional radionecrosis cases were examined for factors associated with radionecrosis and management (Cohort B, n = 148). RESULTS: From Cohort A, 17% developed radionecrosis, with a cumulative incidence at 2 years of 18%. Using Cohort B, multivariable analysis confirmed an association between radionecrosis and elevated lactate dehydrogenase (p = 0.0496) and prior treatment with ipilimumab (p = 0.0319). Radionecrosis was diagnosed based on MRI (100%), symptoms (69%) and pathology (56%). Treatment included corticosteroids, bevacizumab and neurosurgery. CONCLUSIONS: Radionecrosis is a significant toxicity in longer-term melanoma survivors with MBM treated with anti-PD-1 and radiotherapy. Identification of those at risk of radionecrosis who may avoid radiotherapy is required.