Stereotactic Ablative Radiotherapy for Comprehensive Treatment of Oligometastatic Tumors (SABR-COMET): A Randomized Phase II Trial
Stereotactic Ablative Radiotherapy for Comprehensive Treatment of Oligometastatic Tumors (SABR-COMET): A Randomized Phase II Trial
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
Bone -Any bone except femur,35(Gy), in 5 fractions,daily
Brain - Non-radiosurgical,40(Gy) to metastases, in 5 fractions,daily
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)
Inclusion Criteria:
Age 18 or older
Willing to provide informed consent
Histologically confirmed malignancy with metastatic disease detected on imaging. Biopsy of metastasis is preferred, but not required.
ECOG performance status 0-1
Controlled primary tumor
a. defined as: at least 3 months since original tumor treated definitively, with no progression at primary site
All sites of disease can be safely treated based on criteria below
Maximum 3 metastases in any single organ system (i.e. lung, liver, brain, bone)
Life expectancy >6 months
Not a candidate for surgical resection at all sites: surgery to all sites not recommended by multidisciplinary team, or unfit or declining surgery
Prior chemotherapy allowed but no systemic therapy 4 weeks prior to first fraction of radiotherapy, during radiotherapy, or for two weeks after last fraction
Patients with metastases that have been previously treated (e.g. prior resection, Radiofrequency Ablation (RFA) or radiotherapy):
a. If that previously treated metastasis is controlled on imaging, the patient is eligible for this study and that site does not need treatment
a. If that previously treated metastasis is NOT controlled on imaging:
Patient presented at multidisciplinary tumor board or quality-assurance rounds.
Exclusion Criteria:
London, Ontario N6A 4L6, Canada