Predictive and prognostic functions of microtubule-associated protein-tau and topoisomerase IIα protein in early breast cancer
e22169 Background: Topoisomerase IIα protein(topo II) is the molecular target of topo II inhibitors such as anthracyclines and Microtubule-Associated Protein(MAP)-tau protein is associated with taxane sensitivity. Anthracyclins and taxanes are major cytotoxic agents of breast cancer in the adjuvant setting. The aim of this study was to evaluate the predictive and prognostic functions of MAP-tau and topo II in early breast cancers. Methods: Representative breast tumor sections were constructed from paraffin embedded specimens from 78 node positive breast cancer patients. MAP-tau and topo II protein were assessed by immunochemistry using antibody clone 4F1(Affinity BioReagents,USA) and clone Ki-S1 antibody(Dakocytomation,USA). MAP-tau staining of tumor cells was semiquantatively scored as 0, 1+, 2+, 3+ and cases with 0 or 1+ staining intensity were considered MAP-tau negative. Topo II protein over- expression was defined as the detection of nuclear staining in more than median value of evaluated cells. Results: Thirty- four cases (43.6%) of 78 samples showed topo II overexpression and 35 cases(44.9%) showed MAP-tau overexpression in node positive breast cancers. HER2 overexpression was noted in 28 samples (35.9%) and 56 cases (71.8%) were compatible with the luminal type. In 43 patients (55.1%), anthracyclin and taxane were used as adjuvant therapy and in this group, both MAP-tau and topo II overexpression showed lower disease-free survival (DFS) than the others, but statistically not significant. In luminal type, MAP-tau overexpression was poor prognostic factor on DFS in Cox regression.(HR 5.644, 95% CI 1.14–28.07, p=0.034) Conclusions: Topo II overexpression and MAP-tau overexpression in node positive breast cancers were not significant predictive factors for anthracyclin and taxane therapies. As several investigators reported, MAP-tau is associated endocrine therapy sensitivity in patients without chemotherapy, but higher MAP-tau in luminal type was a strong poor prognostic factor in patients who were given chemotherapy and hormonal therapy. No significant financial relationships to disclose.