Positron emission tomography and neoadjuvant therapy of breast cancer

The preliminary study of 18F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma xenografts

OBJECTIVE

The purpose of the preliminary study was to investigate the value of (18)F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts in nude mice models.

METHODS

Twelve BALB/c-nu nude mice were randomly divided into two groups. They were subcutaneously injected with either CNE1 or CNE2 cell suspension. Xenograft volumes were measured after tumor formation. When the tumors reached nearly 10 mm in diameter, they received 15-Gy irradiation. Before and 24 h after irradiation, mice were performed with (18)F-FLT micro-PET/CT. The region of interest (ROI) was manually drawn, and the percent of injected dose per gram of the tumor and muscle in the ROIs was recorded. Tumor-to-muscle ratio (T/M) was calculated and compared with volume changes. Additionally, we also used ten untreated mice as control group.

RESULTS

After irradiation, CNE2 tumors decreased significantly while CNE1 tumors continuously grew and became stable after 1 week. However, in control group, CNE1 and CNE2 tumors continuously enlarged in the observed time. Therefore, we could regard CNE2 group as irradiation responder while CNE1 group as non-responder. In irradiation group, the value of T/M before irradiation (T/M 0) of CNE1 mice was statistically lower than CNE2 mice (1.62 ± 0.38 versus 5.57 ± 1.30; P = 0.004). Besides, T/M decreased significantly in CNE2 group after irradiation (5.57 ± 1.30 versus 3.59 ± 1.06; P < 0.001). By means of a receiver operating characteristic curve, the optimal cut value of T/M 0 and ∆T/M to predict responder was 2.38 and -0.15, respectively (both sensitivity and specificity = 100.0 %).

CONCLUSIONS

(18)F-FLT PET/CT has the potential to predict radiosensitivity in NPC xenografts nude mice models.

Can positron emission tomography/computed tomography with the dual tracers fluorine-18 fluoroestradiol and fluorodeoxyglucose predict neoadjuvant chemotherapy response of breast cancer?--A pilot study

OBJECTIVE

To assess the clinical value of dual tracers Positron emission tomography/computed tomography (PET/CT) (18)F-fluoroestradiol ((18)F-FES) and (18)F-fluorodeoxyglucose ((18)F-FDG) in predicting neoadjuvant chemotherapy response (NAC) of breast cancer.

METHODS

Eighteen consecutive patients with newly diagnosed, non-inflammatory, stage II and III breast cancer undergoing NAC were included. Before chemotherapy, they underwent both (18)F-FES and (18)F-FDG PET/CT scans. Surgery was performed after three to six cycles of chemotherapy. Tumor response was graded and divided into two groups: the responders and non-responders. We used the maximum standardized uptake value (SUVmax) to qualify each primary lesion.

RESULTS

Pathologic analysis revealed 10 patients were responders while the other 8 patients were non-responders. There was no statistical difference of SUVmax-FDG and tumor size between these two groups (P>0.05). On the contrary, SUVmax-FES was lower in responders (1.75±0.66 versus 4.42±1.14; U=5, P=0.002); and SUVmax-FES/FDG also showed great value in predicting outcome (0.16±0.06 versus 0.54±0.22; U=5, P=0.002).

CONCLUSIONS

Our study showed (18)F-FES PET/CT might be feasible to predict response of NAC. However, whether the use of dual tracers (18)F-FES and (18)F-FDG has complementary value should be further studied.