EpCAM expression in lymph node and bone metastases of prostate carcinoma: A pilot study.

Abstract

165 Background: Correct staging of prostate carcinoma has huge treatment implications since metastasized prostate carcinoma cannot be treated curatively. Nowadays, skeletal scintigraphy is the mainstay for the assessment for bone metastases despite its poor sensitivity. Lymph node metastases can be diagnosed accurately with Computed Tomography. However, the gold standard is a pelvic lymph node dissection. A non-invasive diagnostic modality, that can assess both lymph node and bone metastases simultaneously, is preferred. In this retrospective pilot study expression of epithelial cell adhesion molecule (EpCAM) was investigated in lymph node metastases, normal lymph nodes, and bone metastases of prostate carcinoma. Furthermore, EpCAM expression was correlated to clinicopathological parameters. Methods: Lymph node metastases (n = 22) and matched normal lymph nodes (n = 22) were available in 17 patients who underwent a pelvic lymph node dissection because of suspicion of nodal involvement on CT. Bone metastases (n = 24) were available in 24 patients who underwent surgery to confirm the disease or to treat skeletal related events. Immunohistochemistry was performed to determine EpCAM expression. Two researchers, blinded to clinical data, scored the immunoreactivity according to Allred. Sensitivity and specificity of EpCAM immunoreactivity in lymph node and bone metastases was calculated. Fisher’s Exact Test was used to correlate EpCAM expression to the clinicopathological parameters Gleason score, prior radiotherapy and prior hormonal treatment. Results: Sensitivity and specificity of EpCAM expression was 100% in lymph nodes. In bone metastases sensitivity was 92%. No correlation between EpCAM expression and clinicopathological parameters was found. Conclusions: Molecular imaging of EpCAM is promising for prostate carcinoma staging, due to the high sensitivity and specificity in lymph node metastases and the high sensitivity in bone metastases. Even in poorly differentiated metastases and after hormonal treatment and radiotherapy, EpCAM was expressed.