BACKGROUND: The alpha(v)beta(3) integrin is one of the angiogenesis-related membrane proteins highly expressed on the neovasculature of breast cancer and lung carcinomas. Labeling of the alpha(v)beta(3) integrin with (99m)Tc-NC100692 provides a potential tool for imaging angiogenesis and hence the presence of malignant lesions. PURPOSE: To determine the feasibility of detecting metastatic lesions in liver, lung, bone, and brain with scintigraphy using the alpha(v)beta(3)-avid imaging agent (99m)Tc-NC100692 in patients with breast or lung cancer, and to assess its safety profile. MATERIAL AND METHODS: Twenty-five patients--15 with lung cancer and 10 with breast cancer--were recruited at 10 centers. Metastases were newly diagnosed by computed tomography, magnetic resonance imaging, or bone scintigraphy, i.e., the reference standard. Patients underwent whole-body scans of approximately 10-15 min duration beginning at 45 min post-injection and a SPECT acquisition of approximately 30 min beginning at 75 min after injection of up to 1100 MBq (99m)Tc-NC100692. In case of liver metastases, dynamic acquisitions of 15 min were performed starting immediately post-injection. Safety measurements were performed up to 2.5 hours after injection and included hematology, serum biochemistry, coagulation, urine analysis, vital signs, oximetry, 12-lead ECG assessments, and a physical examination. RESULTS: In patients with breast cancer, (99m)Tc-NC100692 scintigraphy detected 1 of 7 liver, 4 of 5 lung, 8 of 17 bone, and 1 of 1 brain metastases. The corresponding numbers for lung cancer patients were 0 of 2, 17 of 18, 2 of 2, and 7 of 9. There was overall stability through the follow-up period for all investigated safety parameters. CONCLUSION: Scintigraphy with (99m)Tc-NC100692 is feasible for detection of lung and brain metastases from breast and lung cancer, while the detection of liver and bone lesions is poor. The use of (99m)Tc-NC100692 is safe and well tolerated.