18 F-Alfatide II PET/CT for Identification of Breast Cancer: A Preliminary Clinical Study.

18 F-Alfatide II has been proven to have excellent clinical translational potential. In this study, we investigated 18 F-Alfatide II for identifying breast cancer and compared the performances between 18 F-Alfatide II and 18 F-FDG. Methods: Forty-four female patients suspected of primary breast cancer were recruited. PET/CT images using 18 F-Alfatide II and 18 F-FDG were acquired within seven days. Tracer uptakes in breast lesions were evaluated by visual analysis, semiquantitative analysis with maximum standardized uptake value (SUVmax ) and mean standardized uptake value (SUVmean). Results: Forty-two breast cancer lesions and 11 benign breast lesions were confirmed by histopathology in 44 patients. Both 18 F-Alfatide II and 18 F-FDG had higher uptake in breast cancer lesions than in benign breast lesions ( P < 0.05 for 18 F-Alfatide II, P < 0.05 for 18 F-FDG). The area under the curve (AUC) of 18 F-Alfatide II was slightly less than that of 18 F-FDG. Both 18 F-Alfatide II and 18 F-FDG had high sensitivity (88.1% vs. 90.5%), high positive predictive value (PPV) (88.1% vs. 88.4%), moderate specificity (54.5% vs. 54.5%), and moderate negative predictive value (NPV) (54.5% vs. 60.0%) for differentiating breast cancer from benign breast lesions. By combining 18 F-Alfatide II and 18 F-FDG, the sensitivity and NPV significantly increased to 97.6% and 85.7%, respectively, with PPV slightly increased to 89.1%, and no change to the specificity (54.5%). The uptake of 18 F-Alfatide II (SUVmax : 3.77±1.78) was significantly lower than that of 18 F-FDG (SUVmax : 7.37±4.48) in breast cancer lesions ( P < 0.05). 18 F-Alfatide II uptake in triple-negative subtype was significantly lower than that in Luminal A and Luminal B subtypes. By contrast, human epidermal growth factor receptor-2 (HER-2) overexpressing subtype had higher 18 F-FDG uptake than other three subtypes. There were 8 breast cancer lesions with higher 18 F-Alfatide II uptake than 18 F-FDG uptake, which all had a common characteristic that HER-2 expression was negative and estrogen receptor (ER) expression was strongly positive. Conclusion: 18 F-Alfatide II is suitable for clinical use in breast cancer patients. 18 F-Alfatide II is of good performance, but not superior to 18 F-FDG in identifying breast cancer. 18 F-Alfatide II may have superiority to 18 F-FDG in detecting breast cancer with strongly positive ER expression and negative HER-2 expression.