The purpose of this study is to prospectively evaluate the feasibility of SBRT for the management of synchronous oligo metastatic liver metastases from colorectal cancers.

This will be a phase II feasibility trial to evaluate ablative radiation for the management of colorectal cancer with potentially resectable/ablatabale synchronous oligo-metastases.

In this study, following completion of the neo-adjuvant component of treatment, patients will be re-staged (as is the current standard of care) and can then proceed for SBRT to the liver lesion. Patients who may have responded very well to the systemic treatment with no-residual disease on re-staging imaging, will use pre-treatment imaging for target delineation. The advantage of SBRT is in the minimally invasive approach to treatment that may be associated with lower morbidity, better quality of life and post treatment morbidity, as well as being significantly less expensive.

The planned course of the neo-adjuvant component of treatment for this study will reflect the NCCN (National Comprehensive Cancer Network) guidelines and will treat rectal cancer patients with a short course of radiation followed by 6-9 cycles of a combination chemotherapy regimen.

For the colon cancer group of patients, all patients will receive 6-9 cycles (2-3 months) of neo-adjuvant systemic chemotherapy as per current standard of care.

Patients with non-progressive disease at that point, will have SBRT for the metastatic lesion followed by surgery for the primary rectal cancer.

Inclusion Criteria:

• Age ≥ 18 years
• ECOG (Eastern Cooperative Oncology Group) 0-2
• Able to provide written informed consent
• 1-5 Liver lesions with max size of ≤5cm for a single lesion and restricted to one lobe of liver; deemed at Multi-Disciplinary Tumor Board (MDT) to be potentially amenable for SBRT with curative intent
• Liver lesion identified within 3 months of diagnosis of primary and deemed at Multi-Disciplinary Tumor Board (MDT) to be potentially amenable for SBRT with curative intent
• Plan for resection of primary with curative intent
• Patients with liver metastases and potentially resectable/ablatable lung mets can be included.
• Colon cancer patients who have undergone upfront resection of primary colonic lesion can be included
• Able and willing to comply with the terms of the protocol including health-related quality of life (HRQoL) questionnaires
• Women of child bearing potential (WOCBP) must have a negative serum (or urine) pregnancy test at the time of screening. WOCBP is defined as any female who has experienced menarche and who has not undergone surgical sterilization (hysterectomy or bilateral oophorectomy or bilateral salpingectomy) and is not postmenopausal. Menopause is defined as 12 months of amenorrhea in a woman over age 45 years in the absence of other biological or physiological causes. In addition, females under the age of 55 years must have a serum follicle stimulating hormone, (FSH) level > 40 mIU/mL to confirm menopause.
• Females must not be breastfeeding
• Male patients should agree to not donate sperm during the study

Exclusion Criteria:

• Extra-hepatic metastases (except potentially resectable lung mets)
• Not a suitable candidate for liver resection surgery
• Not a suitable candidate for SBRT
• Past history of cancer within 5 years (except basal cell carcinoma)
• Patients who have undergone previous surgery or ablation for liver lesions
• Planned simultaneous resection of primary and liver metastases
• Pregnancy
• Patients with Child-Pugh C and documented cirrhosis