ASSOCIATION OF INTRATUMORAL PHARMACOKINETICS OF FLUOROURACIL WITH CLINICAL-RESPONSE

In-vivo fluorine-19 nuclear magnetic resonance spectroscopy (NMRS) allows non-invasive, real-time, chemical identification of specific fluorinated compounds inside human tumours after administration of fluorouracil (5-fluorouracil). Kinetic measures of the administered drug and metabolites allow estimation of the tumoral half-life of fluorouracil. We studied 57 patients by F-19 NMRS immediately after they had received 600 mg/m(2) fluorouracil intravenously. Serial spectra were acquired with the surface coil positioned on the shin above the tumour. We defined an intratumoral half-life of fluorouracil of 20 min or more as indicating trapping of the drug, based on the blood half-life of 8-12 min. 19 patients had intratumoral half-lives indicating trapping of fluorouracil, 27 had half-lives less than 20 min, and 11 had no detectable fluorouracil in their rumours. 8 of 9 evaluable patients whose tumours showed trapping had partial responses to chemotherapy that included fluorouracil compared with only 2 of 25 patients whose tumours did not trap the drug (p = 0.000021). F-19 NMRS can identify patients likely to respond to chemotherapy with fluorouracil and could be used clinically to tailor optimum treatment.