Identification of single nucleotide polymorphisms of the PI3K-AKT-mTOR pathway as a risk factor of central nervous system metastasis in metastatic breast cancer

Publication date: Available online 2 November 2017
Source:European Journal of Cancer
Author(s): Emilie Le Rhun, Nicolas Bertrand, Aurélie Dumont, Emmanuelle Tresch, Marie-Cécile Le Deley, Audrey Mailliez, Matthias Preusser, Michael Weller, Françoise Revillion, Jacques Bonneterre
IntroductionThe PI3K-AKT-mTOR pathway may be involved in the development of central nervous system (CNS) metastasis from breast cancer. Accordingly, herein we explored whether single nucleotide polymorphisms (SNPs) of this pathway are associated with altered risk of CNS metastasis formation in metastatic breast cancer patients.MethodsThe GENEOM study (NCT00959556) included blood sample collection from breast cancer patients treated in the neoadjuvant, adjuvant or metastatic setting. We identified patients with CNS metastases for comparison with patients without CNS metastasis, defined as either absence of neurological symptoms or normal brain magnetic resonance imaging (MRI) before death or during 5-year follow-up. Eighty-eight SNPs of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian (or mechanistic) target of rapamycin (mTOR) pathway genes were selected for analysis: AKT1 (17 SNPs), AKT2 (4), FGFR1 (2), mTOR (7), PDK1 (4), PI3KR1 (11), PI3KCA (20), PTEN (17), RPS6KB1 (6).ResultsOf 342 patients with metastases, 207 fulfilled the inclusion criteria: One-hundred-and-seven patients remained free of CNS metastases at last follow-up or date of death whereas 100 patients developed CNS metastases. Among clinical parameters, hormonal and human epidermal growth factor receptor-2 (HER2) status as well as vascular tumour emboli was associated with risk of CNS metastasis. Only PI3KR1-rs706716 was associated with CNS metastasis in univariate analysis after Bonferroni correction (p < 0.00085). Multivariate analysis showed associations between AKT1-rs3803304, AKT2-rs3730050, PDK1-rs11686903 and PI3KR1-rs706716 and CNS metastasis .ConclusionPI3KR1-rs706716 may be associated with CNS metastasis in metastatic breast cancer patients and could be included in a predictive composite score to detect early CNS metastasis irrespective of breast cancer subtype.



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