PREST: Pain REduction With Bone Metastases STereotactic Radiotherapy: A Phase III Randomized Multicentric Trial

Palliative antalgic oncological treatments, e.g. For patients in the chronic-evolutionary phase of the disease with need for pain control, are a serious problem from the point of view: management, clinical and scientific research. However, they are affecting an ever-increasing volume of patients due to the increased incidence of cancer in all its phases and the potential chronicity of illness linked to new therapies.

The use of palliative anti-radiation radiotherapy treatments potentially involves up to 40% of patients in a Radiotherapy Center. Radiotherapy is commonly used in palliative treatment of symptomatic bone metastases (Furfari A, 2017) being an effective treatment to improve symptoms and consequently improve the quality of life (QoL) of these patients. Due to the peculiar characteristics of the patients who need these treatments, scientific research aimed at optimizing these therapies is a need for assistance and even ethics.

Ideally, this treatment should be as short as possible to re-direct them to systemic therapies or to home care or long-term care systems (e.g.: Hospice). In order to deliver a clinically effective dose in a short period of time, hypofractionated regimens must be used. Stereotactic radiotherapy is a type of radiotherapy that allows to deliver a high equivalent biological dose in a highly conformed manner, with a favorable toxicity profile (Correa RJ, 2016), and generally in a few fractions. The possibility of using special techniques such as stereotactic radiotherapy has been investigated in several phase 2 studies, in terms of symptom response with good results at 3 months (van der Velden JM, 2016) (Murai T1, 2014) (Braam P , 2016) (Deodato F, 2014) (Ryu S, 2014). Further studies have suggested, in order to better manage the toxicity profile linked to the hypofractioned regimen, the possibility of using a hypofractionated regimen over the entire bone compartment and going to over-dose with a stereotaxic regimen only the macroscopically visible disease to the instrumental examinations. In particular, in patients with favorable prognostic scores, this regimen would improve the possible onset of acute and late complications. Although there are indications in the literature (generated by the Consensus Conference) about the radiation treatment schedules to be preferred, there is no globally coded and clinically applied therapeutic prescription standard (Chow E1 & Party, 2012). The most commonly applied conventional radiation treatment schedules include: i) 8 Gy in 1 therapy session; ii) 20 Gy in 5 therapy sessions; iii) 30 Gy in 10 therapy sessions.

With the same pain control, multiple fractionation boards report, according to some authors, better symptom control over time and are therefore very often preferred for patients with a prognosis> 6 months. Routine use of prognostic scores to characterize life expectancy and define the most appropriate treatment regimen is very rarely used in everyday clinical practice.

Modern oncology radiotherapy can take advantage of advanced technologies and exploit the personalization of treatments. To date, some randomized trials are underway investigating the role of stereotactic radiotherapy for these patients compared to conventional approaches, but not all of them use adequate personalization of treatment. Furthermore, none of the ongoing and currently registered trials analyzes the "ii) 20 Gy in 5 treatment sessions" versus stereotactic in the direct comparison between two single randomized arms. The aim of this randomized multicenter prospective trial study is to evaluate the pain control effectiveness of an unconventional fractionation delivered with the most innovative stereotactic technique approach available in this clinical scenario against the conventional one; enrollment of patients will be specifically selected with prognosis> 6 months according to the Mizumoto score (Mizumoto M, 2008) and structural stability defined according to Spine Instability Neoplastic Score (SINS) <7, with indication to radiotherapy on bone metastases. Highlights of this study include: the high level of treatment customization for both accurate selection and ultraconformed radiation therapy planning; the reduction in the number of sessions to which the patient must be subjected, which reduces his discomfort; the approach innovation; the location of the study group (multicentric, in the Italian panorama) in a central position in the international scenario of the specific sector. The results of this trial are potentially "practice-changing".