Fig. 3.

Mutation detection in paired BC and BM samples. A Representative examples of mutation spectra between paired BC/BM samples with identified mutations as (i) T/T, (ii) T/L and (iii) (-/T) with relative intensity on the y-axis and mass/charge on the x-axis. B The frequency (percentages) of the identified mutations for each of the 5 genes according to the ER, PgR and HER2 receptor status in primary BC and in paired BM. The exact number of mutations is presented in Supplementary Table 4. One of the 3 ER-negative/HER2-positive primary BC samples was carrying an ESR1 mutation, whereas no mutations were identified in the other 2 samples and they were not included in the pie-charts. C Kaplan–Meier (Log-rank) survival plots of breast–brain metastasis-free survival (BMFS) and overall survival (OS). Patients carrying ≤ 3 mutations had a significantly better BMFS (p = 0.0001, HR: 0.011, 95% CI: 0.001–0.112), than patients with > 3 mutations. There was no association with OS (p = 0.056, HR: 0.146, 95% CI: 0.020–1.054) and number of mutations