SBRT for Nodal Metastasis

Abstract

<h3>Purpose/Objective(s)</h3> Lymph node metastases (NMs) are a common site of tumor spread that can occur at the time of diagnosis or during systemic therapy or during follow-up with variable incidence based on the primary tumor site, stage, histology, and grading. Stereotactic body Radiation Therapy (SBRT) can be a therapeutic option for NMs in the setting of oligometastatic disease (OMD). The oligometastatic disease is an area of research rapidly evolving in the definition, characterization and treatment. The first end point of this study is to evaluate the outcomes of lymph node metastases treated with SBRT in terms of Local Control (LC), Loco Regional Nodal Control (LRNC), Distant Nodal Control (DNC), Distant Metastasis Free Survival (DMFS), Progression Free Survival (PFS) and Overall Survival (OS). The secondary end point is to identify predictive factors of response and to assess the toxicities. <h3>Materials/Methods</h3> In this study we included patients with a maximum of 5 metastasis and various primary tumors (31% lung, 22% prostate, 13% colon rectal, 10% gynecological, 7% breast, 6% upper GI, 5% genito urinary, 2% H&N, 4% others). Concomitant treatments were allowed. From November 2007 to September 2021, 228 NMs were treated in 174 patients with SBRT (<8 fractions). At time of treatment 49% of patients were classified as oligorecurrent, 41% oligoprogressive, 3% oligometastatic and 7% oligopersistent. The single fraction and multiple fractions were administered respectively in the 22% and 78% of cases. Most represented schedule was 30 Gy in 5 fractions, the medium BED (10) of SBRT was 74,7 Gy (range: 33,6- 120 Gy). <h3>Results</h3> The median follow-up was 22 months (range 0-148 months). Rates of LC at 1, 2 and 3 years were 93%, 89% and 86%. Rates of LRNC at 1, 2 and 3 years were 88%, 81% and 82%. Rates of DNC were at 1, 2 and 3 years 90%, 86%, and 83%. Rates of DMFS were at 1, 2 and 3 years 58%, 49%, and 42%. Rates of PFS were at 1, 2 and 3 years 41%, 28% and 22%. Rates of OS were at 1, 2 and 3 years 73%, 56% and 43%. At univariate analysis, the total number of metastases were associated with worse DMFS (P< 0,0001) and PFS (P = 0,0004). The genitor-urinary and gynecological tumors showed a statistically significant correlation with worse results in terms of DMFS (P = 0,0003), PFS (P = 0,0460) and OS (P = 0,0023). Treatment was well tolerated. The acute toxicities were 9 (4%) cases Grade 1, in the form of pain, fatigue, nausea, vomiting and cough, one case (0.44%) of anemia G2 and one case (0.44%) of death caused by esophageal bleeding, G5. The late toxicity was a case G2 (0.44%) in the form of dyspnea. <h3>Conclusion</h3> In conclusion, our analysis confirmed the efficacy and safety of SBRT in the treatment of NMs. Despite the marked heterogeneity of the included cases and the retrospective nature of the analysis, the results of this study are encouraging. Prospective studies are required to further confirm the benefit of this treatment.