Clinical validation of the influence of P-glycoprotein on technetium-99m-sestamibi uptake in malignant tumors.
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.
Kostakoglu
L
L
Department of Nuclear Medicine, Hacettepe University, Medical Faculty, Ankara, Turkey.
Elahi
N
N
Kïratlï
P
P
Ruacan
S
S
Sayek
I
I
Baltalï
E
E
Sungur
A
A
Hayran
M
M
Bekdik
C F
CF
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
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D009363:Neoplasm Proteins; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi