Carbon-11-Thymidine and FDG to Measure Therapy Response

• Published in: The Journal of nuclear medicine (1978) Vol. 39; no. 10; pp. 1757 - 1762
• Main Authors: Shields, Anthony F, Mankoff, David A, Link, Jeanne M, Graham, Michael M, Eary, Janet F, Kozawa, Susie M, Zheng, Minna, Lewellen, Barbara, Lewellen, Thomas K, Grierson, John R, Krohn, Kenneth A
• Format: Journal Article
• Language: English
• Published: Reston, VA Soc Nuclear Med 01-10-1998; Society of Nuclear Medicine
• Subjects: Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Biological and medical sciences; Carbon Radioisotopes; Carcinoma, Small Cell - diagnostic imaging; Carcinoma, Small Cell - drug therapy; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Humans; Investigative techniques, diagnostic techniques (general aspects); Lung Neoplasms - diagnostic imaging; Lung Neoplasms - drug therapy; Male; Medical sciences; Middle Aged; Miscellaneous. Technology; Radionuclide investigations; Radiopharmaceuticals; Sarcoma - diagnostic imaging; Sarcoma - drug therapy; Thymidine; Tomography, Emission-Computed; Radionuclide study; Antineoplastic agent; Energy metabolism; Fluorine; Treatment efficiency; Malignant tumor; Deoxyribonucleotide; Metabolism; Carbon; Chemotherapy; Proton; Comparative study; Emission tomography
• ISSN: 0161-5505; 1535-5667

This study was performed to determine if PET imaging with 11C-thymidine could measure tumor response to chemotherapy early after the initiation of treatment. Imaging of deoxyriboneucleic acid biosynthesis, quantitated with 11C-thymidine, was compared with measurements of tumor energetics, obtained by imaging with 18F-fluorodeoxyglucose (FDG).
We imaged four patients with small cell lung cancer and two with high-grade sarcoma both before and approximately 1 wk after the start of chemotherapy. Thymidine and FDG studies were done on the same day. Tumor uptake was quantified by standardized uptake values (SUVs) for both tracers by the metabolic rate of FDG and thymidine flux constant (K(TdR)) using regions of interest placed on the most active part of the tumor.
In the four patients with clinical response to treatment, both thymidine and FDG uptake markedly declined 1 wk after therapy. Thymidine measurements of SUV and K(TdR) declined by 64% +/- 15% and 84% +/- 33%, respectively. FDG SUV and the metabolic rate of FDG declined by 51% +/- 9% and 63% +/- 23%, respectively. In the patient with metastatic small cell lung cancer who had disease progression, the thymidine SUV decreased by only 8% (FDG not done). In a patient with abdominal sarcoma and progressive disease, thymidine SUV was essentially unchanged (declined by 3%), whereas FDG SUV increased by 69%.
Images show a decline in both cellular energetics and proliferative rate after successful chemotherapy. In the two patients with progressive disease, thymidine uptake was unchanged 1 wk after therapy. In our limited series, K(TdR) measurements showed a complete shutdown in tumor proliferation in patients in whom FDG showed a more limited decrease in glucose metabolism.