title: Clinical validation of the influence of P-glycoprotein on technetium-99m-sestamibi uptake in malignant tumors.
abstract: We prospectively studied 48 patients with either breast cancer (30 patients) or lung cancer (18 patients) to ascertain the relationship between the degree of accumulation of 99mTc-sestamibi and the expression of p-glycoprotein in tumor tissues.
  
  
  METHODS
  During initial presentation (37 patients) or post-therapy evaluation (11 patients), the patients underwent contemporaneous 99mTc-sestamibi imaging and biopsy (30 patients) or surgery (18 patients). The interval between surgery/biopsy and imaging varied between 3 and 15 days. All patients had radiologically detectable tumors. Immunohistochemical studies were performed on paraffin sections using a monoclonal antibody, JSB-1, developed against the internal epitope of p-glycoprotein. Tumor-to-background ratios were correlated with the level of p-glycoprotein expression determined by immunohistochemical studies.
  
  
  RESULTS
  Our results showed an inverse correlation between the tumor-to-background ratios of 99mTc-sestamibi and the density of p-glycoprotein expression in tumor tissues. The values for the tumor-to-background ratios were significantly lower for those tumors expressing p-glycoprotein at high levels than those with scattered and no expression (p < 0.01 and p < 0.001, respectively).
  
  
  CONCLUSIONS
  Although our results warrant further studies at the molecular level using PCR techniques after the extraction of mRNA, our data strongly suggest that 99mTc-sestamibi imaging is useful to noninvasively determine the presence of multidrug resistance in patients with malignant tumors.
authors.affiliation: Department of Nuclear Medicine, Hacettepe University, Medical Faculty, Ankara, Turkey.
authors.forename: L
authors.initials: L
authors.lastname: Kostakoglu
authors.forename: N
authors.initials: N
authors.lastname: Elahi
authors.forename: P
authors.initials: P
authors.lastname: Kïratlï
authors.forename: S
authors.initials: S
authors.lastname: Ruacan
authors.forename: I
authors.initials: I
authors.lastname: Sayek
authors.forename: E
authors.initials: E
authors.lastname: Baltalï
authors.forename: A
authors.initials: A
authors.lastname: Sungur
authors.forename: M
authors.initials: M
authors.lastname: Hayran
authors.forename: C F
authors.initials: CF
authors.lastname: Bekdik
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism; D018276:Carcinoma, Medullary / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism; D018432:Drug Resistance, Multiple; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D009363:Neoplasm Proteins; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi