Influence of pre-treatment Tumour Growth Rate on objective response of hepatocellular carcinoma treated with transarterial chemoembolization.

INTRODUCTION: To assess the influence of pre-treatment Tumour Growth Rate (TGR) on mRECIST objective response (OR) after a first session of selective trans-arterial chemoembolization (TACE) for the treatment of hepatocellular carcinoma (HCC).

METHODS: 115 patients (101 men [88%], mean 65.1±10.5 years [range 26-87]) with 169 tumours (mean 34.2±29.3mm [10-160]), undergoing a first session of selective TACE for the treatment of HCC between 2011 and 2016, were included. TGR was calculated as the percentage change in tumour volume per month (%/mo) on imaging before treatment. TGR cut-off for prediction of OR was identified by ROC curve analysis.

RESULTS: Overall 88/189 (52%) and 46/189 (27%) tumours showed complete (CR) and partial response (PR) [OR rate 79%], while 32/189 (19%) showed stable disease (SD), and 3/189 (2%) were progressive disease (PD) on CT at 1-month post-TACE. The mean pretreatment TGR was 12.0±15.4 (-3.2-90.4) %/mo. TGR of tumours showing CR, PR, SD, and PD was a mean 13.2±16.4%, 12.1±15.1%, 5.3±4.5%, and 44.8±20.4%, respectively (p<0.001). The three tumours showing PD had TGR values >20%/mo. TGR was significantly higher in tumours with OR (12.8±15.9% vs. 5.3±4.5% in SD, p=0.009). A cut-off value of 6.5%/mo had the highest predictive value of OR (AUROC 0.65±0.05, p=0.009).

CONCLUSION: Pre-treatment TGR is highly variable in HCC before TACE with a U-shaped distribution for the prediction of tumour response. It provides insight into tumour biology that may be used during pre-treatment workup to help stratify patients.