The relationship between chemotherapeutic response and 99Tcm-DTPA-DG uptake in breast cancer model

Objective: It has been reported that 99Tcm-DTPA-deoxyglucose (DG) may be uptaken by tumor cells. This study was to evaluate the feasibility of using 99Tcm-DTPA-DG to assess chemotherapeutic response of tumor. Methods: Twenty-five female nude rats inoculated with MCF-7 cells for 9 d were randomly divided into five groups. The control group was treated with 0.1 mL/kg of saline. The combined chemotherapy group I was administered with 11 mg/kg of Taxol and 4.7 mg/kg of Doxorubicin. The combined chemotherapy group II was injected with 5 mg/kg of Taxol and 2.3 mg/kg of Doxorubicin. The cisplatin group I and II were injected with 8 and 4 mg/kg of cisplatin, respectively. Scintigraphic studies were conducted at 0, 7, 14, 21 and 28 d after the treatments. The radioactivity ratio of tumor to non-tumor (T/ NT) was calculated with region of interest (ROI) technique. After the last imaging the rats were sacrificed. The radioactivity ratios of tumor/blood and tumor/muscle were measured. Tumor volume and thereby the inhibition rate in each group were calculated. Results: Tumors were clearly visualized on the 99Tcm-DTPA- DG images. The distribution of 99Tcm-DTPA-DG demonstrated that chemotherapeutic groups had lower tumor/muscle ratios (t=8.735, 4.826, 3.198) and tumor/blood ratios (t=7.652, 3.976, 3.945) than control group (all P<0.05). The T/NT ratios were significantly lower in the three chemotherapy groups than in control group (F=1018.165, P<0.01), while there was no significant difference of T/NT ratios between cisplatin group II and control group. The T/NT ratio changes were in agreement with the results of tumor volume measurements, except for cisplatin group II. Conclusions: There may be a correlation between 99Tcm-DTPA-DG uptake and therapeutic effects after chemotherapy in tumor tissue. 99Tcm-DTPA-DG might be used to evaluate the therapeutic response of tumor. (authors)