Abstract
AimsTo evaluate the efficacy and toxicity of extracranial stereotactic body radiotherapy (SBRT) in the treatment of oligometastatic lymph node involvement in the mediastinum, retroperitoneum, or pelvis, in a consecutive group of patients from real clinical practice outside clinical trials.MethodsA retrospective analysis of 90 patients with a maximum of four oligometastases and various primary tumors (the most common being colorectal cancers). The endpoints were local control of treated metastases (LC), freedom from widespread dissemination (FFWD), progression-free survival (PFS), overall survival (OS), and freedom from systemic treatment (FFST). Acute and delayed toxicities were also evaluated.ResultsThe median follow-up after SBRT was 34.9 months. The LC rate at three and five years was 68.4 and 56.3%, respectively. The observed median FFWD was 14.6 months, with a five-year FFWD rate of 33.7%. The median PFS was 9.4 months; the three-year PFS rate was 19.8%. The median FFST was 14.0 months; the five-year FFST rate was 23.5%. The OS rate at three and five years was 61.8 and 39.3%, respectively. Median OS was 53.1 months. The initial dissemination significantly shortened the time to relapse, death, or activation of systemic treatment—LC (HR 4.8, p < 0.001), FFWD (HR 2.8, p = 0.001), PFS (HR 2.1, p = 0.011), FFST (HR 2.4, p = 0.005), OS (HR 2.2, p = 0.034). Patients classified as having radioresistant tumors noticed significantly higher risk in terms of LC (HR 13.8, p = 0.010), FFWD (HR 3.1, p = 0.006), PFS (HR 3.5, p < 0.001), FFST (HR 3.2, p = 0.003). The multivariable analysis detected statistically significantly worse survival outcomes for initially disseminated patients as well as separately in groups divided according to radiosensitivity. No grade III or IV toxicity was reported.ConclusionOur study shows that targeted SBRT is a very effective and low toxic treatment for oligometastatic lymph node involvement. It can delay the indication of cytotoxic chemotherapy and thus improve and maintain patient quality of life. The aim of further studies should focus on identifying patients who benefit most from SBRT, as well as the correct timing and dosage of SBRT in treatment strategy.
Highlights
Oligometastatic disease (OD), commonly defined as the presence of five or fewer metastatic lesions located in a limited number of organs [1], is diagnosed more often due to the increased availability of positron emission tomography (PET/CT) scanning, which has become an integral part of the follow-up examination schedule
All patients indicated for Stereotactic body radiotherapy (SBRT) were in good general condition, with a Karnofsky index of at least 70%
In half of the cohort, the first metastases occurred after 12 months
Summary
Oligometastatic disease (OD), commonly defined as the presence of five or fewer metastatic lesions located in a limited number of organs [1], is diagnosed more often due to the increased availability of positron emission tomography (PET/CT) scanning, which has become an integral part of the follow-up examination schedule. OD is supposedly an intermediate step between localized and disseminated cancer [2, 3]. Local therapies such as surgery, radiofrequency ablation (RFA), cryoablation, or targeted radiotherapy have the potential to achieve local control (LC) with minimal toxicity. Stereotactic body radiotherapy (SBRT) is a non-invasive method of treating localized tumor lesions by applying high doses of ionizing radiation in a small number of fractions. This is possible by employing specially equipped linear accelerators, modern immobilization devices, and imaging methods. Compared to standard radiotherapy (RT) techniques, SBRT allows for significantly higher doses to be delivered with less damage to surrounding healthy tissues due to its accuracy [7, 8]
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