Real-Time Tumor-Tracking Radiotherapy and General Stereotactic Body Radiotherapy for Adrenal Metastasis in Patients With Oligometastasis

Abstract

Background:Precise local radiotherapy for adrenal metastasis can prolong the useful life of patients with oligometastasis. The aim of this retrospective, 2-center study was to establish the safety and effectiveness of real-time tumor-tracking radiotherapy and general stereotactic body radiotherapy in treating patients with adrenal metastatic tumors.Materials and Methods:Thirteen lesions in 12 patients were treated with real-time tumor-tracking radiotherapy (48 Gy in 8 fractions over 2 weeks) and 8 lesions in 8 patients were treated with general stereotactic body radiotherapy (40-50 Gy in 5-8 fractions over 2 weeks or 60-70 Gy in 10 fractions over 2 weeks). Overall survival rates, local control rates, and adverse effects were analyzed.Results:The actuarial overall survival rates for all patients at 1 and 2 years were 78.5% and 45.8%, respectively, with a median follow-up of 17.5 months, and the actuarial local control rates for all tumors at 1 and 2 years were 91.7% and 53.0%, respectively, with a median follow-up of 9 months. A complete local tumor response was obtained in 3 tumors treated by real-time tumor-tracking radiotherapy (lung adenocarcinomas with diameters of 35, 40, and 60 mm). There was a statistically significant difference in the local control between the groups treated by real-time tumor-tracking radiotherapy (100% at 1 year) and general stereotactic body radiotherapy (50% at 1 year; P < .001). No late adverse reactions at Grade 2 or higher were reported for either treatment group.Conclusions:This study showed that although both treatments are safe and effective, the real-time tumor-tracking radiotherapy is more effective than general stereotactic body radiotherapy in local control for adrenal metastasis.

Stereotactic body radiotherapy (SBRT) for adrenal metastases of oligometastatic or oligoprogressive tumor patients

“…Limitations to this study were mainly caused by the retrospective nature of this analysis. Patient numbers were rather low, but similar to other studies, as adrenal SBRT is still not offered to many patients [3,21,22,24,36,43,45]. Furthermore, for increasing strength and homogeneity of our study, we only focused our analysis on truly oligometastatic or oligoprogressive patients and excluded all patients who were treated with palliative intent or dose.…”

“…The adrenal glands have been reported to show extensive respiration induced motion of more than 20 mm in several directions [22,43]. To account for target movement due to breathing, nearly all patients were treated with a 4-D-CTbased internal target volume (ITV) concept in our study.…”

“…On the contrary, active motion management strategies like gating and tracking, allow for real-time target monitoring during radiotherapy [22,45]. When applying gating or tracking, the ITV-concept is no longer needed and PTV sizes can be substantially decreased.…”

“…While SBRT is well established and widely applied in the treatment of pulmonary and hepatic oligometastases [17][18][19][20], the literature for adrenal metastases is scarce. Predominantly small and retrospective studies exist which do not primarily focus on oligometastatic or oligoprogressive disease, but also include patients treated with palliative intent [21][22][23][24][25][26][27]. Furthermore, these studies only report limited details on radiotherapy planning and requirement for forced dose restrictions due to the close proximity to radiosensitive organs-at risks (OARs).…”

Clinical efficacy of Stereotactic Body Radiation Therapy (SBRT) for adrenal gland metastases: A multi-center retrospective study from China

“…Recent studies have reported clinical practices of SBRT for different metastases, including the lung, liver, iliac lymph node, brain and bone metastases [15][16][17] . Nevertheless, the efficacy of SBRT for AGM has been evaluated in only a few studies [18][19][20][21][22][23][24][25][26][27][28][29][30][31] . The relevant studies in the past three years have been listed in Table 3.…”