Introduction/Background Defining hormonal receptors’(HR) status plays an important role in the management of patients with breast cancer. A change in these biomarkers’ status between primary and recurrent/metastatic lesions is correlated with major therapeutic and prognostic implications.The aim of this study is to evaluate the prognostic impact of this discordance between the primary and recurrent sites.

Methodology We reviewed the clinical record of 47 patients with locoregional/metastatic relapse of breast disease diagnosed between 2005 and 2020 in Salah Azaiez Institute.

Results Twelve patients(26.7%) had a change in tumor phenotype during recurrence: a switch to a triple negative status was observed in 11 cases.

The median follow-up time was 68 months; the median post-recurrence follow-up time was 17 months. however, the median disease-free interval(DFI) was 34 months . Five-year overall-survival(OS) and post-recurrence-survival(PRS) rates were 60.3% and 15%, respectively.

We demonstrated that primary Her2neu-positive tumor or distant metastasis site were independently associated with worse PRS.

Among the discordant cases, the patients whose tumor phenotype turned into triple-negative had the worst PRS(P=0.05) and OS(P=0.167), when compared with the concordant group.

Univariate analysis demonstrated that impact factors of PRS including recurrent site(P=0.024), ER(P=0.043) and PR(P=0.021) conversion between primary and recurrent/metastatic lesions; in addition to estrogen-receptors-loss(ER)(P=0,048).

The Her2-discordant cases, when compared with the Her2-concordant cases, showed a poorer clinical outcome(median 3 versus 23 months, P<0.0005 and median 48 versus 83 months, P = 0.250, for PRS and OS, respectively).

The PR and ER discordant cases, when compared with the concordant cases, showed a poorer clinical outcome for PRS(median 4 versus 29 months, P = 0.021 and median 4 versus 26, P=0.043).

Overall, a change in HR status resulted in a worse PRS(13.06 versus 32.03 months, P=0.028) and OS(median 53.88 versus 83.14 months, P=0.045).

Conclusion These results reinforce the re-evaluation of the biomarkers status by performing confirmatory biopsies of recurrence, to avoid misdiagnosis of breast cancer relapse, and to optimize treatment.

Disclosures the authors have nothing to disclose.