What is the recommended surveillance protocol for hepatocellular carcinoma (HCC) after Stereotactic Ablative Body Radiation (SABR) therapy?

From the Guidelines

Surveillance for hepatocellular carcinoma (HCC) after stereotactic ablative radiotherapy (SABR) should include multiphasic, cross-sectional imaging of the chest, abdomen, and pelvis every 3 to 6 months for 2 years, then every 6 to 12 months after definitive therapies, as recommended by the National Comprehensive Cancer Network guidelines 1. This approach is based on the consensus that earlier identification of disease, primary or recurrent, may facilitate patient eligibility for investigational studies or other forms of life-prolonging treatment. The preferred method for surveillance following treatment is multiphasic cross-sectional imaging, such as CT or MRI, due to its reliability in assessing arterial vascularity, which is associated with increased risk of HCC recurrence following treatment. Additionally, alpha-fetoprotein (AFP) levels should be measured every 3 months for 2 years, then every 6 to 12 months after definitive therapies, as elevated AFP levels are associated with poor prognosis after treatment. Some studies suggest that MRI may be preferred over multiphase CT in post-treatment surveillance of HCC, especially in patients who have received liver-directed therapy, as it can better assess for tumor recurrence 1. However, the most recent and highest quality study, the NCCN guidelines, recommends multiphasic CT or MRI every 3 to 6 months for 2 years, then every 6 to 12 months after HCC resection 1. It is essential to continue surveillance indefinitely as long as patients remain candidates for additional treatment if recurrence is detected. The surveillance schedule should be tailored to the individual patient's risk factors, such as cirrhosis and/or chronic HBV, and should include regular assessment of liver function and overall health. In cases where recurrence is suspected, multiphase contrast studies are recommended, and in unclear cases, biopsy may be necessary. Overall, the goal of surveillance is to detect recurrence early, when it is more amenable to treatment, and to improve patient outcomes. Key points to consider in surveillance for HCC after SABR include:

• Use of multiphasic cross-sectional imaging, such as CT or MRI
• Measurement of AFP levels every 3 months for 2 years, then every 6 to 12 months
• Consideration of MRI over multiphase CT in post-treatment surveillance, especially in patients who have received liver-directed therapy
• Continuation of surveillance indefinitely as long as patients remain candidates for additional treatment
• Tailoring the surveillance schedule to the individual patient's risk factors and overall health.

From the Research

HCC Surveillance Post SABR

• The decision to treat HCC with SABR is evaluated in a multidisciplinary setting, and the specific treatment chosen depends on the treatment intent and underlying patient clinical factors 2.
• Patients who undergo SABR need continuous imaging evaluation to assess treatment response and to evaluate for recurrence 2.
• SBRT-treated HCC demonstrates unique imaging findings that differ from HCC treated with other forms of treatment, and accurate assessment of treatment response is necessary to guide clinical management 2.
• The optimal imaging surveillance after SABR for HCC is not well established, but studies suggest that CT scans should be ordered routinely in follow-up, with fludeoxyglucose positron emission tomography/CT scans recommended if there is suspicion for local recurrence 3.
• Radiological parameters such as gross vascular invasion, irregular tumor margin, and peripheral ragged enhancement on CT or MRI are associated with non-response after chemoembolization and poor overall survival 4.

Imaging Findings and Treatment Response

• SBRT-treated HCC can demonstrate persistent APHE and washout on short-term follow-up imaging, and an accurate understanding of expected post-SBRT imaging findings is critical to avoid misinterpreting normal post-treatment changes as local progression or viable tumor 2.
• The use of a formal scoring system, informed by validated data, can help classify high-risk imaging features predictive of local recurrence 3.
• CT findings suspicious for local recurrence include infiltration into adjacent structures, bulging margins, sustained growth, mass-like growth, spherical growth, craniocaudal growth, and loss of air bronchograms 3.

Prognostic Factors and Survival

• Factors such as Eastern Cooperative Oncology Group performance status and tumor response are independent prognostic factors for overall survival in patients with HCC treated with SABR 5.
• Tumor size and T3a disease are also associated with significantly worse survival 6.
• A prognostic scoring system based on radiological parameters such as gross vascular invasion, irregular tumor margin, and peripheral ragged enhancement can help predict overall survival in patients with HCC treated with chemoembolization 4.