Natural history of hepatocellular carcinoma after stereotactic body radiation therapy

Abstract

Purpose To determine the long-term natural history of size change in SBRT-treated HCC to identify an imaging biomarker to help assess treatment response. Methods This was a retrospective cohort study of consecutive HCCs treated with SBRT from January 2008 to December 2016 with either 2 years post-treatment MRI follow-up or post-treatment resection histology. Size, major features for HCC, and mRECIST and LI-RADS v.2018 treatment response criteria were assessed at each post-treatment MRI. Local progression, distant progression, and survival were modeled with Kaplan Meier analyses. Results 56 HCCs met inclusion criteria. Mean baseline HCC diameter was 30 mm (range: 9-105 mm). At 3 months, 76% (N = 43) of treated HCCs decreased in size (mean reduction: 8 mm, range: 5-99 mm) and 0% (N = 0) increased in size. By 24 months, 11% (N = 5) had increased in size and were considered local progression. APHE remained in 77% (43/56) at 3 months, 38% (19/50) at 12 months, and 23% (11/47) at 24 months. mRECIST-defined viable disease was observed in 77% (43/56) at 3 months and 20% (9/47) at 24 months. LI-RADS v.2018 criteria identified viable or equivocal disease in 0% at 3 months and 10% (5/47) at 24 months. Conclusion Gradual loss of APHE and slow decrease in size are normal findings in HCCs treated with SBRT, and persistent APHE does not indicate viable disease. mRECIST is not accurate in the assessment of HCC after SBRT due to an overreliance on APHE to define viable disease. Increasing mass size or new nodular APHE at the treatment site may indicate local progression.

Stereotactic radiotherapy for hepatocellular carcinoma: Expanding the multidisciplinary armamentarium

“…Treated lesions showing persistent but stable or reducing enhancement and size should not be interpreted as residual disease. Mendiratta‐Lala and colleagues reported serial magnetic resonance imaging changes in 56 patients post‐SABR with 77% demonstrating persistent APHE at 3 months, decreasing to 38% at 12 months and 23% at 24 months 65 . This study highlighted that the modified response evaluation criteria in solid tumors (mRECIST) will have poor accuracy, particularly in the first year following SABR.…”

“…Mendiratta-Lala and colleagues reported serial magnetic resonance imaging changes in 56 patients post-SABR with 77% demonstrating persistent APHE at 3 months, decreasing to 38% at 12 months and 23% at 24 months. 65 This study highlighted that the modified response evaluation criteria in solid tumors (mRECIST) will have poor accuracy, particularly in the first year following SABR. The authors proposed that an increase in mass size (as per conventional RECIST) and new nodular APHE or increasing intensity of APHE within the treated mass are more indicative of local recurrence.…”

Hepatocellular carcinoma Liver Imaging Reporting and Data Systems treatment response assessment: Lessons learned and future directions

“…The treated tumor should gradually decrease or stay stable in size during the time period where treatment response is evolving (Figure 6 ). Imaging features suggesting recurrent disease after SBRT include: Increase in size of the treated tumor or new or increasing intensity of APHE after treatment[ 53 ]. Although the treated HCC often demonstrates persistent APHE after SBRT, the degree, or intensity, of APHE often decreases as it resolves.…”

Radiation Therapies for the Treatment of Hepatocellular Carcinoma

“…After SBRT, APHE with or without “washout” can persist for up to and occasionally greater than a year, although persistent APHE gradually decreases in intensity over time 30 . Early posttreatment, geographic APHE surrounding the treated tumor is common and likely represents hyperemia; over time this converts to progressive delayed‐phase geographic enhancement, likely secondary to radiation fibrosis, often associated with capsular retraction and peripheral intrahepatic biliary dilatation 31 .…”

“…2). 30 Imaging features suggesting local disease progression after SBRT include increasing size of the treated tumor or new or increasing intensity of APHE after treatment 10…”