LAUSR

Background/Aim: The optimal method to evaluate response of neuroendocrine liver metastases (NELM) to radiation treatment (RT) is unknown; tumor perfusion parameters were evaluated by using dynamic contrast-enhanced computed tomography (DCE-CT) to correlate with efficacy in a prospective pilot study utilizing everolimus with radiotherapy for NELM. Patients and Methods: Fourteen patients with progressive NELM received everolimus for 28 days prior to, concurrent with, and 14 days following radiation. Patients had a DCE-CT at baseline (t0), prior to radiation (t1) and 7 days after radiation (t2). Per lesion response was evaluated per standard response evaluation criteria (RECIST v1.1). Median statistics of the perfusion parameters were tabulated and included: blood flow (BF), blood volume (BV), and permeability (PS). Correlations between the parameters and the maximum percent change in size of the NELM at 12-months were explored. NELM not treated with radiation served as an internal control. Results: Twenty-one treated NELM in 10 patients were evaluable. Compared to t0, BV increased at t1 (median 11%, range -15 to +37%, p=0.59), and then decreased significantly at t2 (median -8.4%, range -29 to +5.4%, p<0.03). A trend of increased BV in internal controls at each time point supports that the observed effect is due to radiation. Conventional objective response rate was 33%; no progression was seen within 12-months. Conclusion: Changes in DCE-CT were observed in patients receiving everolimus and radiation for NELM, with BV decreasing significantly following radiotherapy. Given the challenges in assessing response in NELM using traditional response evaluation criteria in any context, DCE-CT appears to be a promising modality.