Stereotactic Ablative Radiotherapy for Comprehensive Treatment of Oligometastatic Tumors (SABR-COMET)

Overview

Stereotactic Ablative Radiotherapy (SABR) is a new radiation treatment that delivers high-dose, precise radiation to small tumors in 1-3 weeks of treatment. This new technique can potentially allow radiation treatments to be focused more precisely, and delivered more accurately than with older treatments. This improvement could help by reducing side effects and by improving the chance of controlling the cancer by more precisely treating the cancer. The purpose of this study is to compare SABR with current approaches of chemotherapy and conventional radiotherapy to assess the impact on overall survival and quality of life.

TREATMENT PLAN 6.0.1 Standard Arm (Arm 1) Radiotherapy for patients in the standard arm should follow the principles of palliative radiotherapy as per the individual institution, with the goal of alleviating symptoms or preventing imminent complications. Patients in this arm should not receive stereotactic doses or radiotherapy boosts. Treatment recommendations are as follows: Brain: Whole brain radiotherapy i.e. 20 Gy in 5 fractions, 30 Gy in 10 fractions Lung: Palliative radiotherapy as per 2011 consensus guidelines.15 i.e. 8 Gy in 1 fraction, 20 Gy in 5 fractions, 30 Gy in 10 fractions Bone: Palliative radiotherapy as per 2011 consensus guidelines.16 i.e. 8 Gy in 1 fraction (most common), 20 Gy in 5 fractions, 30 Gy in 10 fractions Liver: 20 Gy in 5 fractions if standard institutional practice 6.0.2 Treatment Planning for Standard Arm Treatment planning is to be done using CT simulation or conventional simulation (fluoroscopy) as per individual institutional practice. Simple beam arrangements, such as parallel opposed beams, are favored wherever possible. 6.1 Experimental Arm (Arm 2) All treatments in this study are based on current protocols in clinical use at the LRCP and VUmc for treatment of lung,17 liver,18 brain,19,20 and spinal cord21 metastases. The guiding principle for radiotherapy is to achieve disease control but to minimize any potential adverse impact on quality of life. Concurrent chemotherapy or targeted therapy at the time of radiotherapy is not permitted within the 4 weeks prior to SABR. Hormone therapy is permitted. 6.1.1 Dose/Fractionation Lung- tumors 3 cm or less surrounded by lung parenchyma, 54(Gy) in 3 fractions * Abutting chest wall or \>3 cm, 55(Gy)in 5 fractions, every second day * Within 2 cm of mediastinum or brachial plexus, 60(Gy),8\* fractions, every second day Bone -Any bone except femur,35(Gy), in 5 fractions,daily * vertebral body,16-20(Gy)in 1 fraction, single dose, or 30Gy in 3 fractions, every second day Brain - Non-radiosurgical,40(Gy) to metastases, in 5 fractions,daily * If whole brain treated, then simultaneous boost to each lesion,20 Gy whole brain (optional), in 5 fractions, daily * Radiosurgical, ≤1 cm, 22-24(Gy), in 1 fraction, \>1 and ≤2 cm, 22-24(Gy) in 1 fraction \>2 and ≤ 3 cm, 18-20(Gy) in 1 fraction Optional whole brain to follow (see text) Liver-LRCP site: Dose is based on calculated normal tissue probability of \<5%,Every second day * other sites 45-60(Gy), in 3-8 fractions, every second day Adrenal, 60 (Gy), in 8 fractions, every second day (If whole brain treated, then simultaneous boost to each lesion) 6.1.2 Immobilization Treatment will be setup using reproducible positioning, verified using an on-line protocol, for all patients in this study. Immobilization may include a custom immobilization device, such as thermoplastic shell or vac-lok bag, as per individual institutional practice when delivering SABR. Some centers do not use immobilization devices and have demonstrated high degrees of accuracy; this is acceptable in this study. 6.1.3 Imaging/Localization/Registration All patients in Arm 2 will undergo planning CT simulation. 4-dimensional CT will be used for tumors in the lungs or liver. Axial CT images will be obtained throughout the region of interest. For centres using stereotactic radiosurgery platforms, real-time tumor tracking and orthogonal imaging systems are permitted. Any center which is not yet experienced in lesions at any specific sub-site (e.g. adrenal metastases) shall be eligible to participate by including only patients with lesions at other pre-specified sites It is strongly recommended that the doses to organs at risk are not to be exceeded - in some specific cases, this may require lower doses or higher fractionations than listed here. Such changes in dose will require approval of one of the local principal investigators. (see section 6.2)