FLUORINE-18-FLUOROURACIL TO PREDICT THERAPY RESPONSE IN LIVER METASTASES FROM COLORECTAL-CARCINOMA

Prediction of chemotherapy response is still a problem in oncological patients. Methods: Studies with PET and F-18-fluorouracil (FU) were us ed for measurements of drug concentrations in patients with liver meta stases from colorectal carcinoma. The PET data obtained before onset o f FU chemotherapy were correlated to the growth rate of the metastases after therapy, The final evaluation included 25 metastases obtained i n 17 patients, CT preceded the first chemotherapeutic cycle and was re peated within 3-11 mo after onset of treatment. The uptake of the cyto static agent was evaluated in the liver metastases using the SUV at 12 0 min after tracer infusion. Tumor growth rate of the metastases was c alculated based on CT volumetric data. Results: The trapping of F-18-F U was highly variable even for multiple metastases in the same patient s. Six metastases with high F-18-FU uptake values exceeding 3.0 SUV co rrelated with negative growth rate values, 5 of 25 metastases with int ermediate uptake values ranging from 2.0-3.0 SUV were associated with almost stable growth rate values nearly zero and 14 of 25 metastases w ith low uptake values < 2.0 SUV demonstrated positive growth rate valu es. Only metastases with a F-18-FU uptake exceeding 3.0 SUV at 120 min postinjection demonstrated a response to therapy. A significant corre lation of 0.86 (p < 0.001) was found between the F-18-FU uptake values in the metastases measured before chemotherapy and the growth rate of the lesions after treatment. Conclusion: The data show, that FU chemo therapy outcome can be predicted using a single PET study with F-18-FU before onset to therapy.