[Correlation between the incidence of PIK3CA mutations in breast cancer and histopathological characteristics of the tumor].

To determine the presence of mutations in exon 9 (encoding the helical domain) and exon 20 (encoding the kinase domain) of phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) gene in DNA obtained from paraffin embedded tissue from patients with carcinoma of the mammary gland and to correlate results with clinicopathological characteristics of cancer.,Prospective clinical study.,Department of Molecular Biology, Department of Obstetrics and Gynecology, Jessenius Faculty of Medicine, Commenius University, Martin, Slovak Republic.,In set of 95 tissue samples from patients with breast cancer, mutations in exon 9 and 20 were analysed by sequencing. We also observed the associations between mutations and histopathological characteristics of tumor.,Overall, mutations were present in 25.3% (24/95) of PIK3CA gene, of this 14.7% (14/95) of mutations were located in exon 9 and 10.5% (10/95) of mutations were in exon 20. We detected three "hotspot" mutations, two were located in exon 9 (E542K, E545K) and the third mutation was found in exon 20 (H1047R). Mutations in exon 9 showed significant correlation with lower grade(p = 0.0074) and pN status without metastases(p = 0.0415). Mutations in exon 20 were associated with higher age of patient (p = 0.0249). The E545K mutation correlated with lower grade (p = 0.0013) and pN status (p = 0.0232) particularly; the H1047R mutation was significantly more frequent in lobular type of breast cancer (p = 0.0354).,The PI3K signaling pathway plays a critical oncogenic role in the development of human breast cancer and the prevalence of its deregulation advocates its potential as a feasible therapeutic target. In our study we demonstrate a significant correlation between the presence of PIK3CA mutations and some clinicopathological characteristics of tumour. We have shown that the mutations in exon 9 of PIK3CA were associated with favourable prognostic factors.,"hotspot" mutation, PIK3CA, PI3K pathway, breast cancer.