ONCOLOGY, O. Alonso

Abstracts XIX Brazilian Congress of Nuclear Medicine

7. ONCOLOGY

4.3 - Tc-99m MIBI SCINTIGRAPHY IN ADVANCED BREAST CANCER: PREDICTION OF CHEMOTHERAPY RESPONSE

O. Alonso, L. Delgado, F. Mut, I. Alonso, G. Lago, M. Núñez, P. Guisoli, G. Sabini, I. Muse, E. Touya. - Nuclear Medicine Center and Department of Clinical Oncology of the Clinical Hospital, University of Uruguay, Montevideo, Uruguay.

oalonso@hc.edu.uy

Tc-99m MIBI has been reported to be extruded from tumor cells by the P-glycoprotein (Pgp), encoded by the MDR1 gene. This is one of the most frequent mechanisms of multidrug resistance in advanced breast cancer (ABC). The aim of the present study was to investigate the possible relation between MIBI tumor uptake and chemotherapy response using Pgp-substrate drugs. We studied 30 lesions (17 breast tumors and 12 axillary) corresponding to 17 patients with ABC: Ten patients with advanced local and regional disease and 7 patients with local, regional and metastatic disease. Images were obtained 2-8 days before chemotherapy using a dose of 740 MBq of Tc-99m MIBI, 10 minutes and 1 hour post injection. Tumor-to-normal ratios at 10 minutes were significantly higher in responding lesions than in non responding (1.95, 1.4-2.9 vs. 1.35, 0-1.6; median, range respectively; p=0.000092). This data suggests that Tc-99m MIBI scintigraphy can be a relevant tool for treatment planning in ABC.