RESUMEN
BACKGROUND: The differential expression of oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2) or Ki-67 between primary tumour and the recurrence has been described. We aimed to determine these changes and their prognostic implications. PATIENTS AND METHODS: We retrospectively reviewed 45 breast cancer patients with relapsed biopsy that were classified into local relapse (LR) or metastatic disease (MD) groups. We analyzed the conversion rate and the value of the immunophenotype of the primary tumour and the relapse as a prognostic factor for relapse-free survival (RFS), progression-free survival (PFS) and overall survival (OS). RESULTS: The conversion rate was 34.8% for Ki-67, 20% for ER, 20% for PR, and 15.6% for HER2. For the LR group, the RFS was 71.9 months and the OS was 141.6 months, without statistical differences according to the immunophenotype of the primary or the relapsed biopsy. For the MD group, the PFS was 20.8 months. According to immunophenotype of the relapse, the PFS were ER+ 24.7 months vs. ER- 9.3 months; PR+ 25.1 months vs. PR- 12.7 months without statistical differences according to HER2 or Ki67. The OS for MD group was 54.4 months without statistical differences according to immunophenotype. CONCLUSION: The characteristics of breast cancer can change over the time. Variations of the ER or PR status in MD group have prognostic value for PFS. To perform a biopsy of relapses is warranted in order to establish the prognostic of the current disease, and probably a more accurate treatment.