The purpose of this study was to evaluate the efficacy of
somatostatin receptor scintigraphy (SRS) in imaging
metastases in patients with advanced
breast cancer (BC), and assess the relationship between exposure to
chemotherapy and hormonotherapy with overexpression of
somatostatin receptor (SS-R) on the
breast cancer cell surface. Twelve patients with metastatic
breast cancer were intravenously (i.v.) injected with In-111 pentatreotide (120 MBq). Early and later images were obtained with a double-head
gamma camera equipped with medium-energy collimators. SPECT was performed when needed. Imaging results were compared with computed tomography and bone scan. Uptake levels were evaluated by site-specific visual analysis. Metastatic
breast cancer can be visualized with SRS. Global sensitivity of imaging was 80% and specificity for correct prediction of
tumor absence was 100%. Sensitivity was significantly higher for bone and lung
metastases. SRS results related to the expression of SS-R on metastatic cell surfaces did not evidence a relationship with the
biologic characteristics of the primary BC and
drug exposure. In our series, SRS quantitative analysis demonstrated that
tumor metastases differ greatly in uptake levels. Fifteen percent of metastatic sites in our series showed strong uptake. Our data support the important specificity of SRS in identifying BC
metastases, mostly in cases of bone and
lung disease, as well as the role of SRS in predicting responsiveness of metastatic BC cells to treatment with
somatostatin analogues (SS), when SS-Rs are overexpressed on cell surfaces. If our results are confirmed in large scale studies, SRS shows the potential to treat selected patients with overexpressed SS-R on their tumoral cells with designed target
therapies with SS analogue.