Early complete tumor response as a survival predictor in hepatocellular carcinoma patients receiving stereotactic body radiation therapy.

BACKGROUND AND PURPOSE

To evaluate the different response patterns after Stereotactic Body Radiation Therapy (SBRT) and their predictive value in local control and progression of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Seventy-two HCC patients who were treated with SBRT during 2015-2020 were included in this retrospective study. The assessment was made using MRI, CT, and PET-CT. Local and systemic responses were determined according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria during follow up. Patients were categorized as early responders (complete response during 6 months after radiotherapy) or non-early responders (the rest of the patients). Prognostic factors were determined using multivariate logistic models.

RESULTS

The median follow-up was 24.0 months (range, 7.7-74.5 months). We found that 84.7%（61/72) of patients achieved a complete response. Early responses occurred in 45 patients (45/72, 62.5%), and they had 1-, 2-, and 5- year intrahepatic outfield-free survival (OutFFS) rates of 86.2%, 80.3%, and 76.3% vs. 55.3%, 44.7%, and 33.5% in non-early responses patients, whereas the 1-, 2-, and 5- year distant metastasis-free survival (DMFS) were 95.5%, 84.5% and 79.5% and 74.1%, 56.2% and 56.2%, respectively. The 1-, 2-, and 5-year overall survival (OS) were 97.7%, 92.1%, 79.1%, and 85.2%, 53.8%, and 40.3%, respectively. Multivariate analysis revealed that early tumor response was an independent predictor of OutFFS, DMFS, and OS.

CONCLUSIONS

Early complete tumor response within 6 months after radiotherapy predicted better intrahepatic outfield-free survival, distant metastasis-free survival, and overall survival outcomes. Confirmation is warranted for early response on SBRT to guide decision making.