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. 2012 Feb 13;14(1):R28.
doi: 10.1186/bcr3113.

PIK3CA mutation impact on survival in breast cancer patients and in ERα, PR and ERBB2-based subgroups

Affiliations

PIK3CA mutation impact on survival in breast cancer patients and in ERα, PR and ERBB2-based subgroups

Magdalena Cizkova et al. Breast Cancer Res. .

Abstract

Introduction: PIK3CA is the oncogene showing the highest frequency of gain-of-function mutations in breast cancer, but the prognostic value of PIK3CA mutation status is controversial.

Methods: We investigated the prognostic significance of PIK3CA mutation status in a series of 452 patients with unilateral invasive primary breast cancer and known long-term outcome (median follow-up 10 years).

Results: PIK3CA mutations were identified in 151 tumors (33.4%). The frequency of PIK3CA mutations differed markedly according to hormone receptor (estrogen receptor alpha [ERα] and progesterone receptor [PR]) and ERBB2 status, ranging from 12.5% in the triple-negative subgroup (ER-/PR-/ERBB2-) to 41.1% in the HR+/ERBB2- subgroup. PIK3CA mutation was associated with significantly longer metastasis-free survival in the overall population (P = 0.0056), and especially in the PR-positive and ERBB2-positive subgroups. In Cox multivariate regression analysis, the prognostic significance of PIK3CA mutation status persisted only in the ERBB2-positive subgroup.

Conclusions: This study confirms the high prevalence of PIK3CA mutations in breast cancer. PIK3CA mutation is an emerging tumor marker which might become used in treatment-choosing process. The independent prognostic value of PIK3CA mutation status in ERBB2-positive breast cancer patients should be now confirmed in larger series of patients included in randomized prospective ERBB2-based clinical trials.

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Figures

Figure 1
Figure 1
Whole population survival curves. (a) Metastasis-free survival curves of patients with PIK3CA wild-type and -mutated tumors. (b) Metastasis-free survival curves of patients with exon 9 PIK3CA-mutated tumors, exon 20 PIK3CA-mutated tumors, and PIK3CA wild-type tumors. Comparison of these curves did not show any statistically significant difference. PIK3CA, phosphatidylinositol 3-kinase, catalytic, alpha polypeptide gene.
Figure 2
Figure 2
Subgroup analysis survival curves. (a) Metastasis-free survival curves of progesterone receptor-positive (PR+) patients with PIK3CA wild-type and -mutated tumors. (b) Metastasis-free survival curves of ERBB2+ patients with PIK3CA wild-type and -mutated tumors. PIK3CA, phosphatidylinositol 3-kinase, catalytic, alpha polypeptide gene.

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