PET/CT Vs. CT: Comparing Treatment Response for Malignant Pleural Mesothelioma

A recent research study evaluated the efficiency of various imaging techniques criteria in evaluating treatment response and projecting prognosis ().

The research paper on this new study was published in Oncotarget's Volume 15 on June 20, 2024, entitled, “Comparison of FDG-PET/CT and CT for evaluation of tumor response to nivolumab plus ipilimumab combination therapy and prognosis prediction in patients with unresectable malignant pleural mesothelioma.”

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Malignant pleural mesothelioma (MPM) is a highly aggressive tumor with low survival outcomes observed in patients.

Patients with a diagnosis of pleural mesothelioma undergo a series of tests to identify the most suitable plan of action and way forward. For individuals with tumors that are considered unresectable, meaning they cannot be surgically removed, the available treatment options are restricted to medical and radiation therapies ().

In a recent retrospective analysis, investigators Kazuhiro Kitajima, Kozo Kuribayashi, Toshiyuki Minami, Hiroyuki Yokoyama, Akifumi Nakamura, Masaki Hashimoto, Takashi Kijima, Seiki Hasegawa, Hayato Kaida, and Koichiro Yamakado from Hyogo Medical University and Kindai University Faculty of Medicine investigated the efficacy of two imaging methods in assessing patients with inoperable malignant pleural mesothelioma (MPM) who were receiving nivolumab plus ipilimumab combination therapy as their initial treatment. The study aimed to determine the impact of these techniques on treatment response and prognosis prediction for individuals affected with this aggressive malignancy.

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Imaging Techniques used for Comparison:

FDG-PET/CT (imPERCIST): This technique uses fluorodeoxyglucose positron emission tomography (FDG-PET) criteria, i.e., immunotherapy-modified PET response criteria in solid tumors (imPERCIST)
CT (mRECIST): Morphological computed tomography (CT) criteria, i.e., modified response evaluation criteria in solid tumors (mRECIST)

“Results for malignant pleural mesothelioma (MPM) patients following first-line treatment with nivolumab plus ipilimumab obtained with immunotherapy-modified PERCIST (imPERCIST), shown by [18F] (FDG-PET/CT), and modified RECIST (mRECIST), shown by CT, were compared for response evaluation and prognosis prediction.”

A total of 26 patients diagnosed with MPM, consisting of 23 males and 3 females, with a median age of 73.5 years, were given a combination therapy of nivolumab and ipilimumab, as they were not eligible for curative surgery. Imaging scans such as FDG-PET/CT and diagnostic CT were conducted at the beginning and after 2–4 treatment cycles. Therapeutic response assessments were based on imPERCIST and mRECIST criteria. Progression-free survival (PFS) and overall survival (OS) analyses were carried out using log-rank and Cox methods.

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How Did the Two Imaging Techniques Compare

The imPERCIST method identified nine cases of progressive metabolic disease (PMD), eight of stable metabolic disease (SMD), four of partial metabolic response (PMR), and five of complete metabolic response (CMR). In comparison, mRECIST revealed that nine patients had progressive disease (PD), nine had stable disease (SD), seven showed partial response (PR), and one had complete response (CR).

Despite a high level of agreement (κ = 0.827), imPERCIST correctly identified a higher percentage of cases with CMR (15.4%). After a median follow-up of 10.0 months, 15 patients experienced disease progression and eight succumbed to MPM. With both, progression-free survival (PFS) and overall survival (OS) were significantly longer in patients without progression (CMR/PMR/SMD, CR/PR/SD, respectively) as compared to PMD/PD patients (imPERCIST p < 0.0001 and p = 0.015, respectively; mRECIST p < 0.0001 and p = 0.015, respectively).

The researchers concluded stating, “For unresectable MPM patient examinations, FDG-PET and CT provide accurate findings for evaluating tumor response and also prognosis prediction following first-line nivolumab plus ipilimumab immunotherapy (approximately three cycles) ().”

References:

Comparison of FDG-PET/CT and CT for evaluation of tumor response to nivolumab plus ipilimumab combination therapy and prognosis prediction in patients with unresectable malignant pleural mesothelioma - (https://pubmed.ncbi.nlm.nih.gov/38900646/)
Study Finds FDG-PET/CT and CT Both Provide Accurate Mesothelioma Evaluation - (https://mesothelioma.net/mesothelioma-news/study-finds-fdg-pet-ct-and-ct-both-provide-accurate-mesothelioma-evaluation/)

Source-Medindia