Evaluation of a new 99mTc-Bombesin analog in differentiation of malignant from benign breast tumors

Introduction: The gastrin releasing peptide (GRP) receptor is over expressed in a variety of common human tumors. Radiolabeled bombesin analogues have exhibited high binding affinity for these receptors. The aim of this study was to assess the value of a new 99mTc-bombesin analog in the differentiation of malignant from benign breast tumors. Methods: 99mTc-bombesin scans were performed in 21 patients (45±21years) with breast tumor. Post-injection of 555-740 MBq 99mTc-bombesin, the dynamic imaging of the chest with 60 seconds for each frame up to 20 minutes was acquired. Subsequently, 360◦ image SPECTs of the chest was performed in 120 steps, 20 seconds per projection. In addition, whole-body anterior and posterior views were obtained 60 and 180 min after injection. Definite diagnosis was based on excisional biopsy and histopathological examination. Results: Thirteen patients demonstrated breast carcinoma and 8 patients were diagnosed as benign lesions. 11 out of 13 patients with breast carcinoma showed radiotracer uptake in the breast lesion. Nine out of 13 patients with breast carcinoma showed axillary lymph node involvement from which only two revealed radiotracer accumulation in the axillary lesion. All patients with benign lesions revealed negative scan. Delayed planar whole body images showed no additional diagnostic information in comparison to one-hour images. The sensitivity, specificity, PPV and NPV of 99mTc-bombesin scan were 84.6%, 100%, 100% and 80%, respectively. Conclusion: Our data suggest that this new 99mTc-bombesin analog could be useful in SPECT imaging of primary breast cancer.