The aim of this study is to investigate the effect of MRI-guided adaptive stereotactic radiotherapy on local control, survival, and toxicity in the treatment of oligometastatic cancer to the abdomen.

This is an Australian-led multi-centre Phase 2 randomised controlled trial. The aim of this study is to investigate the effect of MRI-guided adaptive stereotactic radiotherapy on LC, survival, and toxicity in the treatment of oligometastatic cancer to the abdomen.

This study will provide one of the first high level phase 2 randomised evidence required to demonstrate this new technology improves patient clinical outcomes and inform the selection of patients for MRI-Linac treatment.

The primary objective is to evaluate the effect of MRI-guided adaptive stereotactic radiotherapy on 2 year LC of treated lesion(s) in patients with abdominal oligometastatic or primary liver cancer.

Aim 1: Quantify the effect of MRI-guided stereotactic radiotherapy on patient outcomes. Patient outcomes will be determined by measuring LC, survival, and safety (toxicity).

Aim 2: Quantify patient dose and cancer targeting accuracy. The ability of MRI-Linacs to treat more patients to a higher dose than standard linacs through adaptive dose-escalation and improved target coverage will be quantified. The delivered dose for each treatment arm will be compared.

Aim 3: Explore functional MRI biomarkers of radiotherapy response prediction. Candidate functional biomarkers of tumour perfusion and diffusion will be identified.

Inclusion Criteria:

• Aged 18 years or older

• Patients with diagnosis of oligometastatic disease from primary colorectal, upper gastrointestinal (e.g. gastric, oesophagus, pancreatic), breast, non-small cell lung, renal cell, or gynaecological malignancy. Oligometastatic disease with controlled primary disease* and maximum total of 5 metastatic lesions in a maximum of 2 different organ systems in any of the following sites:

  1. Liver
  2. Adrenal
  3. Abdomino-pelvic lymph node
  4. Other abdominal site e.g. pancreatic, renal.
  5. Other pelvic site
  6. Bony or lung is allowed only if in conjunction with an abdominal site above

• De novo or metachronous oligometastatic disease where the original tumour site has been treated with curative intent.

  • Controlled primary disease in metachronous oligometastastic disease defined as at least 3 months since original tumour treated with curative intent and no progression at primary site
  • Controlled primary disease in de novo oligometastatic disease defined as primary tumour site treated with curative intent and no progression at primary site

• Oligometastatic disease: Histological confirmation of primary malignancy (histological confirmation of metastasis is not mandatory but should be performed in any situation where there is any diagnostic uncertainty).

• All oligometastatic sites treatable with SABR.

OR

• Patients with oligo-progressive / oligo-persistent disease in maximum total of 2 oligo-progressive abdominal metastases and in a maximum 2 different organ systems
• Visible imaging defined targets and suitable for treatment with SABR
• Childs Pugh A to B7 (in case of liver treatment)
• ECOG 0 -2
• Patient consented

Exclusion Criteria:

• Contra-indication to MRI
• Previous high dose radiotherapy to a site requiring stereotactic treatment (including SIRTEX). Further SABR treatment of lesions previously treated with SABR or high dose radiotherapy is not permitted in this trial.
• Substantial overlap with a previously treated high dose (definitive or stereotactic dose) radiation volume.
• Primary prostate cancer, carcinoid tumours, germ cell tumours, lymphoma, small cell tumours
• Pregnant women
• Complete response of metastatic disease to systemic therapy (i.e. no target for SABR)
• Competing medical co-morbidity with a more limited prognosis than the cancer diagnosis