Radiological assessment of response to neoadjuvant transcatheter hepatic therapy with irinotecan-eluting beads (DEBIRI(®)) for colorectal liver metastases does not predict tumour destruction or long-term outcome.

INTRODUCTION: Transcatheter hepatic therapy with irinotecan-eluting beads (DEBIRI(®)) allows targeted delivery of irinotecan direct to liver tissue and colorectal liver metastases (CRLM). Accurate assessment of tumour response to therapy is vital to guide optimal treatment. Preliminary work has suggested existing criteria for radiological response may not reflect pathological response after neoadjuvant DEBIRI. This study assessed the relationship between existing and novel radiological response criteria and pathological tumour response as well as long-term outcome.
METHODS: Patients with easily resectable CRLM were treated with DEBIRI 4 weeks prior to resection and pathological tumour response graded using a validated system. Radiological response was assessed using RECIST and novel morphological response criteria.
RESULTS: Twenty-two patients with 37 lesions were treated with DEBIRI. Median residual tumour was 20% (range 0-80), median necrosis 45% (10-100) and median fibrosis 10% (10-70). Twenty patients (91%) demonstrated stable disease by RECIST, with 11 (50%) demonstrating partial morphological response. Neither radiological response criteria correlated with pathological response. Overall median disease free survival (DFS) was 13.6 months (95% CI 4.7-22.5). Radiological response was not associated with DFS.
CONCLUSION: Existing criteria reporting short-term radiological response to DEBIRI do not accurately predict pathological tumour response or long-term outcome. Further work is necessary to define the optimum timing and method of assessing response to DEBIRI.