Case Report-Staged brachytherapy achieving complete metabolic response in unresectable oligometastatic colorectal cancer to the liver

Liver is the most common site for metastasis from colorectal cancer (CRC). Non-surgical treatment options for oligometastatic CRC confined to the liver which represents an intermediate state in the metastatic cascade are fast expanding. Currently, several liver-directed local therapeutic options are available, such as hepatic arterial infusion (HAI) therapy, radio-frequency ablation (RFA), transarterial chemoembolization (TACE), stereotactic body radiotherapy and high dose rate brachytherapy (HDRBT). Many factors such as patient's fitness, liver function (LF), tumour size, location of the tumour in the liver and scheduling of systemic therapy need to be considered when selecting patients for surgery or local liver-directed therapy. This case report illustrates a successful local treatment with staged HDRBT for a large and unresectable, liver only oligometastatic disease from CRC. This patient underwent 4 cycles of chemotherapy (FOLFOX 4) followed by primary tumour resection and first stage of HDRBT to liver for a residual 14 cm tumour after the chemotherapy. After completing a further 4 cycles of chemotherapy with the same regimen, the tumour remained stable at 8 cm. She underwent a second stage of HDRBT to the same lesion and a repeat PET-CT scan done 8 weeks after the second HDRBT showed complete metabolic response. To our knowledge, this is the largest CRC metastatic liver lesion that has been successfully treated with HDRB.