Stereotactic body radiotherapy treatment of extracranial metastases

Abstract

Radiotherapy is an integral treatment for patients with metastatic cancer, although it is usually reserved for palliation of pain, dyspnoea, oedema, bleeding and neurological symptoms. However, the administration of high-precision radiotherapy, termed stereotactic body radiotherapy (SBRT), has the potential to significantly affect the disease course for some patients with metastatic cancer by delivering high doses of radiation to the secondary tumours with limited high-dose delivery to adjacent healthy tissues. Indeed, such accurate delivery has been firmly established as a therapy for medically inoperable early-stage non-small-cell lung cancer. To date, the technique has demonstrated improvements in controlling metastasis and, in some cases, improved palliation compared with conventionally fractionated radiotherapy. Active areas of research in SBRT include patient selection for curative intent, optimization of SBRT planning techniques, dosing schema and integration of SBRT into systemic therapies. Given the improvements in cytotoxic and targeted therapies over the past decade, studies testing the careful integration of SBRT into standard systemic therapy regimens are needed. Further investigations are also needed to understand the basic biological mechanisms underlying SBRT because they are likely to be different to those mechanisms in conventional radiotherapy.

Stereotactic Ablative Radiation Therapy as First Local Therapy for Lung Oligometastases From Colorectal Cancer: A Single-Institution Cohort Study

“…Patients affected with <5 pulmonary nodules might be in a condition recently defined as oligometastatic disease (2), being suitable for a combination of systemic and metastases-directed local therapies (3)(4)(5). Surgery is the standard therapeutic option, based on the findings of large retrospective studies and few prospective trials.…”

New challenges in high-energy particle radiobiology

“…Interestingly, SBRT commonly uses a non-uniform dose distribution in the tumour to achieve sharp edges on the border of the target volume. 56 The excess dose in the central region of the target may indeed be already acting, in current SBRT practice, as a dose-painting for the hypoxic fraction. 57 Animal experiments comparing SBRT and CPT at high dose per fraction are necessary to clarify this issue and for a full exploitation of CPT in radiosurgery for both malignant and benign diseases.…”

Outcomes of Single Fraction Stereotactic Ablative Radiotherapy for Lung Metastases

“…These findings are still not fully validated, as they mainly come from uncontrolled non-randomized studies with the primary endpoint of local control, and a miscellaneous cohort of patients has been recruited so far (5). In most of the clinical trials, SABR was delivered in few fractions (3)(4)(5)(6)(7)(8)(9)(10), with a local control probability at 1 year in the range 70-90% (7)(8)(9)(10). Single fraction SABR has been less investigated (11,12), even if it is attractive for several clinical considerations: high patients' compliance and acceptance of treatment, the possibility to treat more than 1 lesion in few days, the lower cost, the lower machine workload and an easier combination with systemic therapies.…”

“…Patients affected with 1-5 metastatic pulmonary nodules might be in a condition recently defined as oligo-metastatic disease (2,3), and are often treated with a combination of systemic and metastasis-directed therapies (2)(3)(4)(5). Surgical removal of limited pulmonary metastases usually is the first therapeutic option (6), and radiation was rarely used until recent years, when the emerging alternative represented by Stereotactic Ablative Radiation Therapy (SABR) has been considered with increasing interest, as potentially equally effective and less toxic, especially in elderly patients or in patients with important comorbidities.…”