P-glycoprotein and multidrug resistance-related protein expressions in relation to technetium-99m methoxyisobutylisonitrile scintimammography findings

The purpose of this study was to retrospectively study 48 patients with inf iltrating ductal breast cancer to evaluate the relationship between the deg ree of accumulation of technetium-99m methoxyisobutylisonitrile (Tc-MIBI) a nd P-glycoprotein (Pgp) or multidrug resistance-related protein (MRP) expre ssion in breast cancer tissues. Before surgery or biopsy, all 48 patients u nderwent scintimammography started 10 min after the injection of Tc-MIBI. T umor:background (T:B) ratios were calculated from the Tc-MIBI scintimammogr aphy, Immunohistochemical analysis was performed on the pathological specim ens of the 48 breast tumors to determine Pgp and MRP expression. According to the results of immunohis tochemical analysis, the 48 breast cancers were separated into four groups: (a) group 1, 12 cancers with both positive Pgp expression and positive MRP expression; (b) group 2, 12 cancers with posit ive Pgp expression and negative MRP expression; (c) group 3, 12 cancers wit h negative Pgp expression and positive MRP expression; and (6) group 4, 12 cancers with both negative Pgp expression and negative MRP expression. Amon g the four groups, the T:B ratio was lowest in group 1 (1.13 +/- 0.10) and highest in group 4 (2.17 +/- 0,14), respectively (P < 0,05), The T:B ratios of groups 2 (1.30 +/- 0.25) and 3 (1.32 +/- 0.26) were between those of gr oups 1 and 4, Our data confirmed that Tc-MIBI scintimammography is useful f or determining Pgp and MRP expression in patients with breast cancers.