Molecular Imaging Insight - March 2008 - (Page 10) ADDiTioNAL RESouRCES: Siemens Mi university by J O N at h a N b at C h e L O r Clinical Study Digest The following clinical studies cite PET/CT’s success in lymphoma, soft-tissue sarcoma, cervical and colon cancer and intestinal graft-versus-host disease. LYMPHoMA Revised Response Criteria for Malignant Lymphoma J Clin Oncol 25:579-586 Standardized response criteria are used to interpret and compare clinical trials and for the approval of new therapeutic agents by regulatory agencies. The increased use of PET, immunohistochemistry (IHC), and flow cytometry has driven the creation of new standardized response criteria for malignant lymphoma, according to a special article published in the Feb. 10, 2007 issue of the Journal of Clinical Oncology. In 1999, an international working group (IWG) of clinicians, radiologists and pathologists with expertise in the evaluation and management of patients with non-Hodgkin’s lymphoma (NHL) published guidelines for response assessment and outcomes measurement. However, “they were subject to considerable inter and intraobserver variation and recommended technologies, such as gallium scans, that are no longer considered state-of-the-art,” the authors wrote. “Several points were subject to misinterpretation, notably the application of the complete remission/unconfirmed (CRu), and the recommendations did not include assessment of extranodal disease.” The IWG, recognizing that the guidelines needed to encompass NHL patients treated with PET, IHC, and flow cytometry, established an international harmonization project to issue recommendations. For NHL patients treated with PET or PET/CT, the following guidelines were released: 1. PET is strongly recommended before treatment for patients with routinely FDG-avid, potentially curable lymphomas (such as diffuse large B-cell lymphoma [DLBCL], Hodgkin’s lymphoma) to better delineate the extent of disease; however, currently it is not mandated because of limitations imposed by cost and availability. For incurable, routinely FDG-avid, indolent, and aggressive histologies (such as follicular lymphoma and mantle-cell lymphoma), and for most variably FDG-avid lymphomas, the primary end points for clinical trials generally include progression-free survival (PFS), event-free survival, and overall Malignant lymphoma. Source: Beijing Hospital, Beijing, China. survival. PET is not recommended before treatment unless response rate is a major end point of the trial. 2. Numerous studies have demonstrated that PET performed after one to four cycles of multi-agent chemotherapy predicts therapeutic outcome; however, no currently available data demonstrate improvement in results by altering treatment based on this information. Until such data exist, this practice should be restricted to clinical trials evaluating PET in this context. 3. PET is essential for the post-treatment assessment of DLBCL and Hodgkin’s lymphoma because a complete response is required for a curative outcome. However, PET is recommended in the other, incurable histologies only if they were PET positive before treatment and if response rate is a primary end point of a clinical study. 4. Current data are inadequate to recommend routine surveillance PET scans after the restaging study. To minimize the frequency of post-therapy inflammatory changes, PET scans should not be performed for at least 3 weeks, and preferably 6 to 8 weeks, after completion of therapy, the authors recommended. SoFT-TiSSuE SARCoMA Reduction of Glucose Metabolic Activity is More Accurate than Change in Size at Predicting Histopathologic Response to Neoadjuvant Therapy in High-Grade Soft-Tissue Sarcomas Clin Cancer Res 2008;14(3) Although changes in tumor size are a common visual indicator of response to treatment in solid tumors, this correlates poorly with histopathologic response to neoadjuvant therapy in patients with soft-tissue sarcomas. Quantitative FDG-PET demonstrates significantly more accuracy than size-based criteria and should be considered as a modality to monitor treatment response in patients with high-grade, soft-tissue sarcomas, according to a prospective study published in the February 2008 issue of the Clinical Cancer Research. From January 2005 to January 2007, 42 patients with resectable biopsy-proven, high-grade soft-tissue sarcoma underwent an FDGPET/CT scan before and after neoadjuvant treatment at the University of California, Los Angeles. Neoadjuvant therapy consisted of systemic chemotherapy with or without radiation therapy. MolecularImaging.net 10 Molecular Imaging Insight | March 2008 http://www.mi-university.com http://jco.ascopubs.org/cgi/reprint/25/5/579.pdf http://clincancerres.aacrjournals.org/cgi/content/abstract/14/3/715 http://MolecularImaging.net
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