Prognostic significance of heparanase expression in primary and metastatic breast carcinoma

High levels of heparanase are detected in many types of tumors, associated with bad prognosis. Typically, heparanase levels are evaluated in a biopsy taken from the primary lesion, whereas its expression by the resulting metastases is most often unresolved. This becomes critically important as anti-heparanase compounds enter advanced clinical trials. Here, we examined the expression of heparanase in pairs of primary and the resulting distant metastases of breast carcinoma. Interestingly, we found that heparanase expression in the metastatic lesion does not always reflect its expression in the primary tumor. Accordingly, in some cases, the primary lesion was stained positive for heparanase while the metastasis stained negative, and vice versa. Heparanase discordance occurred in 38% of the patients, higher than that reported for hormone receptors, and was associated with bad prognosis. Thus, examination of heparanase levels in the tumor metastases should be evaluated for most efficient precision medicine applying heparanase inhibitors. Furthermore, we found that in stage I breast cancer patients strong heparanase staining is associated with shorter overall survival. Thus, heparanase levels can assist in the diagnosis and in determining the necessity and type of treatment in early stage breast cancer.