Prior systemic treatment increased the incidence of somatic mutations in metastatic breast cancer

Publication date: January 2018
Source:European Journal of Cancer, Volume 89
Author(s): Takeo Fujii, Naoko Matsuda, Miho Kono, Kenichi Harano, Huiqin Chen, Rajyalakshmi Luthra, Sinchita Roy-Chowdhuri, Aysegul A. Sahin, Chetna Wathoo, Aron Y. Joon, Debu Tripathy, Funda Meric-Bernstam, Naoto T. Ueno
BackgroundUnderstanding the biology of breast cancer is important for guiding treatment strategies and revealing resistance mechanisms. Our objectives were to investigate the relationship between previous systemic therapy exposure and mutational spectrum in metastatic breast cancer and to identify clinicopathological factors associated with identified frequent somatic mutations.MethodsArchival tissues of patients with metastatic breast cancer were subjected to hotspot molecular testing by next-generation sequencing. The variables that significantly differed (P < 0.05) in univariate analysis were selected to fit multivariate models. Logistic models were fit to estimate the association between mutation status and clinical variables of interest. Five-fold cross-validation was performed to estimate the prediction error of each model.ResultsA total of 922 patients were included in the analysis. In multivariate analysis, previous systemic treatment before molecular testing (N = 186) was associated with a significantly higher rate of TP53 and PIK3CA mutations compared with the lack of systemic treatment (P < 0.001 for both).ConclusionSystemic treatment exposure is an independent risk factor for high rates of TP53 and PIK3CA mutation, which suggests the importance of testing samples after systemic therapy to accurately assess mutations. It is worth testing the gene profile when tumours become resistant to systemic treatments.



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