The clinical utility of 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography-computed tomography (PET-CT) scans in the management of patients with chronic lymphocytic leukemia (CLL) has not been clearly defined. CLL cells typically have low FDG avidity and the addition of the PET component has not been shown to improve the utility of CT scans in the management of patients with CLL. However, patients with CLL are at increased risk of developing FDG avid complications including more aggressive lymphomas, other second malignancies, and infections for which FDG PET-CT scans are a useful imaging modality. We hypothesized that FDG PET-CT scans are sensitive tests for evaluation of these complications in patients with CLL.
This observational study was performed with IRB approval. We studied all 4030 CLL patients seen at least once in the Division of Hematology at Mayo Clinic Rochester between January 1, 2006 and December 31, 2011 using data prospectively collected into the Mayo Clinic CLL database. We reviewed the clinical and radiological records of the 272 (7%) patients who underwent 526 FDG PET-CT scans of the trunk during this time period to determine the indication for PET-CT scan, results of imaging, and the effects of the use of PET/CT scan on management.
Four hundred and seventy two (90%) of the 526 PET-CT scans were reported as abnormal. Of these, 78 (17%) scans were useful in directing a tissue biopsy of high FDG avidity lesions. Of the 37 (8%) positive PET-CT scans that facilitated the diagnosis of new complications of CLL, 21 (4%) scans led to a diagnosis of diffuse large B cell lymphoma and 9 (2%) scans led to a diagnosis of a solid malignancy. The FDG component of 22 PET-CT scans done because of clinical suspicion of complications of CLL were negative, and thus useful in management of these patients. PET-CT scans showed progressive CLL in 138 (29%) studies but in these patients, the PET component of the scan did not provide additional information about the status of the patients' CLL compared to the CT component alone.
FDG PET-CT scans are not of proven value in staging CLL or determining response to treatment. However, our data suggest that they could be of considerable value in evaluation for complications, especially more aggressive lymphomas, other cancers, and infections that complicate the course of CLL.
Off Label Use: Phase I study using PGG beta glucan in CLL. Zent:Biothera: Research Funding; Genzyme: Research Funding; Genentech: Research Funding; Novartis: Research Funding; GlaxoSmithKline: Research Funding.
Asterisk with author names denotes non-ASH members.
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