Selective Interarterial Radiation Therapy (SIRT) in Colorectal Liver Metastases: How Do We Monitor Response?

Radioembolisation is a way of providing targeted radiotherapy to colorectal liver metastases. Results are encouraging but there is still no standard method of assessing the response to treatment. This paper aims to review the current experience assessing response following radioembolisation. A literature review was undertaken detailing radioembolisation in the treatment of colorectal liver metastases comparing staging methods, criteria, and response. A search was performed of electronic databases from 1980 to November 2011. Information acquired included year published, patient numbers, resection status, chemotherapy regimen, criteria used to stage disease and assess response to radioembolisation, tumour markers, and overall/progression free survival. Nineteen studies were analysed including randomised controlled trials, clinical trials, meta-analyses, and case series. There is no validated modality as the method of choice when assessing response to radioembolisation. CT at 3 months following radioembolisation is the most frequently modality used to assess response to treatment. PET-CT is increasingly being used as it measures functional and radiological aspects. RECIST is the most frequently used criteria. Conclusion. A validated modality to assess response to radioembolisation is needed. We suggest PET-CT and CEA pre- and postradioembolisation at 3 months using RECIST 1.1 criteria released in 2009, which includes criteria for PET-CT, cystic changes, and necrosis.