The PI3K-Akt cascade is a key signaling pathway involved in cell proliferation, survival, and growth. Activating PIK3CA mutations have been reported in breast carcinoma (BC). The aim of this study was to characterize the PIK3CA mutations at exons 9 and 20 in a series of 176 sporadic and 22 hereditary BCs and to correlate the results with clinicopathologic parameters and survival. In sporadic BC, 68 missense mutations were detected. PIK3CA mutations were significantly associated with ER+ in HER2-negative cases. A higher frequency of PIK3CA mutations was present in lobular carcinoma compared with ductal carcinoma (50% vs. 35%). There was no association between the survival and PIK3CA mutational status. In hereditary BC, PIK3CA mutations were found only in the BRCA2 group. The PIK3CA mutation seems to characterize the luminal-type BC, in both sporadic and BRCA2 mutated forms, and is absent in the basal-type BC, in both the sporadic and BRCA1 mutated forms.
*Division of Surgical, Molecular and Ultrastructural Pathology, Department of Oncology
‡Department of Oncology, Medical Oncology Unit, University of Pisa and University Hospital of Pisa
†Department of Experimental Medicine, Sapienza University of Rome, Polo Pontino, I.C.O.T, Latina
§Department of Clinical, Morphological and Technological Sciences, University of Trieste
∥Surgical Pathology Unit, ASL1 Massa-Carrara, Tuscany, Italy
Reprints: Claudio Di Cristofano, MD, Department of Experimental Medicine, Sapienza University of Rome, Polo Pontino, I.C.O.T, Via F. Faggiana, 34 0400, Latina, Italy (e-mail: firstname.lastname@example.org).