TU-G-BRA-06: PET-Based Treatment Response Assessement for Neoadjuvent Chemoradiation for Pancreatic Adenocarcinoma

Authors


Abstract

Purpose:

To address the limitations of the conventional response evaluation criteria in solid tumors (RECIST), and validate PET response criteria in solid tumors (PERCIST1.0). We analyze the relationship between the pathological treatment response (PTR) and PERCIST1.0 for patients treated with neoadjuvent chemoradiation (nCR) for pancreatic adenocarcinoma.

Methods:

The pre- and post-nCR CT and PET data for a total of 8 patients with resectable, or borderline resectable pancreatic head adenocarcinoma treated with nCR were retrospectively analyzed. These data were compared with the PTR which were graded according to tumor cell destruction (cellularity), with Grade1, 2 or 3 (G1, G2 or G3) for good, moderate, and poor responses, respectively. RECIST-based PET (RECISTPET), and PERCIST1.0 were defined using lean body mass normalized SUV (nSUVlb). RECIST-based CT (RECISTCT) was defined by contouring the whole pancreas head (CTPH). Pre- and post-nSUVlb and SUVbw, PERCIST 1.0, were correlated with PTR using Pearson's correlation coefficient test.

Results:

The average mean and SD in nSUVlb for all 8 patients analyzed were lower in post-nCR (1.35±0.34) compared to those at pre-nCR (1.38±0.20). Using PERCIST1.0, 5/8 patients showed stable metabolic disease (SMD), 2/8 partial metabolic response (PMR), and 1/8 progressive metabolic disease (PMD). Using RECISTPET 4/8 showed stable disease (STD), 4/8 partial response (PR), whereas 8/8 showed stable disease (STD) using RECISTCT. PTR were correlated with PERCIST1.0 (R=0.3780/P=0.6071). Pathological tumor size was correlated with RECISTCT (R=0.0727/P=0.8679), and RECISTPET, R=−0.3333/P=0.3798.

Conclusion:

Chemoradiation treatment response assessment based on metabolic tumor activities using PRECIST1.0 and RECISTPET appears to provide better agreement with pathological assessment as compared to the conventional CT-based assessment using RECISTCT. The integration of these additional radiographic metrics in assessing treatment response to nCR for pancreatic adenocarcinoma may provide a promising strategy to better select those patients most suitable for therapeutic intensification.

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