Purpose/Objective(s)

While stereotactic ablative radiotherapy (SABR) has emerged as a treatment option for hepatocellular carcinoma (HCC), there are limited data on treatment response evaluation. Functional imaging techniques are increasingly being used to monitor response to therapy. The aim of this study was to evaluate response of the target tumor by functional magnetic resonance imaging (MRI) including diffusion-weighted imaging and its impact on local control in patients with HCC after SABR.

Material/methods

Between Dec 2008 and Nov 2014, 31 HCC patients with 37 tumors underwent SABR using Cyberknife radiosurgery system in our institute. The median radiation dose was 45 Gy (range: 30-60 Gy), 6-12.5 Gy per fraction. We collected clinical and treatment-related and factors including age, ECOG performance status, α-fetoprotein (AFP) level, Child-Pugh score, CLIP score, and AJCC stage. All patients had pretreatment and 1- to 3- month follow-up MRI. Response using volumetric functional apparent diffusion coefficient (ADC) was assessed in all target tumors. Local control was defined as the target tumors with no increase size of enhancing part on contrast-enhanced images.

Results

At the last follow up, 16 patients died. The median survival was 13.7 months, with 1-year and 2-year OS rate of 62.9% and 40.0%, respectively. There were 7.4% complete response, 70.4% partial response, 14.8% stable disease, and 7.4% disease progression. There were 8 target tumors with local failure and 2-year local control rate was 73.8%. There was a trend of better 2-year local control in tumors with post-treatment ADC value increase > 10%, compared with those <10% (88.9% vs 64.4%, p = 0.071).

Conclusions

Functional imaging techniques have a potential role in evaluation of treatment response in patients with HCC after SABR. After SABR, the increase of ADC value > 10% had marginally improved local control. A further large-scale study to identify the predictive value of parameters in functional MRI in validated.

Acknowledgements

We would like to give special thanks to Benjamin Yen, professor in University of California, San Francisco, for his guidance and help

References

No reference found.