Stereotactic Body Radiotherapy (SBRT) for Adrenal Metastases: Practice Patterns at Community-Based Radiotherapy Centers
International Journal of Radiation Oncology, Biology, Physics
Purpose/Objective(s): To analyze SBRT of adrenal metastases at freestanding centers within a large network in the USA, in order to guide institutional recommendations. Materials/Methods: We interrogated records of patients treated with SBRT to adrenal metastases from January 2019 to June 2022 from a database of 13,363 patients who were treated with SBRT at 21 communitybased centers clustered into five regions within a network. We reported patient characteristics, frequency, survival rate, and biologically effective dose (BED10) prescribed, respiratory motion capture according to region and treatment year. Survival was calculated by Kaplan-Meier estimates. Results: A total of 271 patients were treated to metastatic adrenal lesions (2.0% of all SBRT patients). Median age was 69.8 years (range 32-96). Frequency of treatment increased by an average of 4.5% per year over the period. Table 1 gives the frequency of primary tumor sites, histological types, and dose fractionations. It also shows the range of BED10 used. 91% received five fractions, and 6% received 3 fractions. Median BED10 was 72 Gy (mean 68.0 Gy SD = 18.7). The most common regimen was 8 Gy x 5 (n = 75, 28%), but ranged from 5 Gy x 5 (n = 20) to 10 Gy x 5 (n = 34). BED10 varied according to geographic region ranging from 61.2 Gy to 73.0 Gy (p = 0.01). Median BED was 72 or above in 2 of 5 regions and less than 72 in 3 regions. Respiratory motion capture simulation was done in 65.1% of cases and frequency varied across the 5 locations as shown in Table1 from 93.3% in region 1 to 41.7% in region 5 (p<.0001). 4D CT simulation was used in 46.2% of cases and use was relatively stable over time: 52.8% in July to December 2020 and 40.9% from January to June 2022 with no trend over time: p = .7635 At median follow-up 6.6 months (range 0.3-48.5), 203 (74.9%) of patients were alive with a median overall survival of 24.3 months. 1-year and 2-year survival was 72.7% and 51.5% respectively. Use of respiratory motion simulation was not significantly associated with survival p = 0.47. Conclusion: Despite variation in BED10 and respiratory motion management, 2-year overall survival was over 50% in patients treated with SBRT for adrenal metastases in a large community network. Further study will address refinement of recommendations regarding dose and other treatment characteristics and expansion of clinical research in this setting.
Ahamad A, Salenius S, Ramanathan S, Kestin LL. Stereotactic body radiotherapy (SBRT) for adrenal metastases: practice patterns at community-based radiotherapy centers. Int J Radiat Oncol Biol Phys. 2023 Oct;117(2 Suppl.):e82. doi:10.1016/j.ijrobp.2023.06.831