FLT PET assesses treatment response on tumor growth—not size—with non-Hodgkin's lymphoma

Researchers call imaging 'promising, sensitive tool' for individuals with diffuse large B-Cell lymphoma, issue study at SNM's 53rd Annual Meeting June 3–7 in San Diego

SAN DIEGO, Calif.--Positron emission tomography (PET)--with the radiolabeled thymidine analog [18F]Fluorothymidine (FLT)--is "a promising, sensitive tool" for assessing drug effects on tumor growth in patients with diffuse large B-cell lymphoma, according to a study released at SNM's 53rd Annual Meeting June 3–7 in San Diego.

"Conventional imaging modalities--such as computed tomography, ultrasound and magnetic resonance tomography--determine response to therapy by changes in tumor size," said Ken Herrmann, resident with the nuclear medicine clinic at the Technical University in Munich, Germany. "However, changes in tumor proliferation may represent a more sensitive tool in differentiating non-responding tumors," added the co-author of "Change of Tumor Cell Proliferation During R-CHOP Chemotherapy of Diffuse Large B-Cell Lymphoma (DLBCL) Measured by 18FLT PET." He indicated, "Our results need to be confirmed by future studies comprising a larger patient population and a variety of different therapy approaches."

Diffuse large B-cell lymphoma is one of some 35 different types of non-Hodgkin's lymphoma, and it accounts for about 3 in 10 of all NHL cases. DLBCL can occur at any time between adolescence and old age, and it is slightly more common in men than in women. DLBCL, like NHL, is a cancer that starts in lymphoid tissues, which includes the lymph nodes and other organs that are part of the body's system for forming blood and protecting against germs. About 59,000 new cases of non-Hodgkin's lymphoma are reported in this country annually, and almost 20,000 people will die from the disease this year.

In their study, researchers evaluated FLT PET to see if it "allows monitoring early response to therapy in patients with DLBCL lymphoma," said Herrmann. They monitored 17 patients who were treated with Rituximab immunotherapy combined with CHOP chemotherapy (R-CHOP), one of the most common chemotherapy regimens for treating NHL. Treatment with the antibody Rituximab led to a temporary increase of FLT uptake in several patients, perhaps reflecting an upregulation (an increase in the number of receptors on the surface of target cells) of DNA synthesis within the lymphoma cell compartment or a recruitment and proliferation of tumor-invading lymphocytes, noted Herrmann. "In contrast, CHOP led to a rapid decrease of FLT uptake early after application--presumably due to a reduction of tumor cell proliferation," he said.

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Abstract: K. Herrmann, B. Krause, H. Wester, H. Wieder and M. Schwaiger, Nuclear Medicine, Technical University, Munich, Germany; T. Dechow, M. Schoeffel, C. v. Schilling and C. Peschel, Medizinische Klinik, Rechts der Isar, Technical University, Munich, Germany; and W. Weber, Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, Calif., "Change of Tumor Cell Proliferation During R-CHOP Chemotherapy of Diffuse Large B-Cell Lymphoma (DLBCL) Measured by 18FLT-PET," SNM's 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 486.

About SNM

SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease; metabolic imaging for heart disease; neuroendocrine and brain imaging, new agents for imaging infection and inflammation; and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.

SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed journal in the field; host the premier annual meeting for medical imaging; sponsor research grants, fellowships and awards; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced--and continue to explore--biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.


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