With the implementation of anti-HER2 therapies in clinical practice, the OS of patients with HER2(+) breast carcinoma significantly improves. The aim of this retrospective analysis is to asses the prognostic value of dynamic HER2 status conversion among the patients with metastatic disease, treated in our institution.
The data are obtained from the medical documentation of the patients with breast cancer in early, locally advanced and metastatic stage. Descriptive statistical analysis is used. As positive is defined the conversion from HER2 (-) to HER2 (+) status and as negative is defined the conversion from HER2 (+) to HER2 (-) receptor status. The HER2 status is determined by IHC or in situ hybridization method.
From m.07.2006 to m.07.22 in our institution are treated 423 patients with BC. In 18 cases we found conversion in HR and/or HER2 receptor status. HER2 conversion is seen in 61% (11/18), respectively positive conversion in 6 pts, negative conversion in 3 pts and in 2 of the cases we observed positive and negative HER2 conversion in the course of treatment. The group of patients with HER2 conversion is heterogeneous. It includes women with locally advanced BC, treated with NACT (3/11), patients with synchronous (2/11) and metachronous (4/11) metastatic disease, where the receptor status has been reassessed in the course of treatment and women with resected oligometastatic disease (2/11), treated with adjuvant anti-HER2 therapy. The mean duration of anti-HER2 therapy among the patients with metastatic disease and positive HER2 conversion is 31.1 m. The mOS among the patients with HER2 conversion and metastatic disease is 80.1 m. For the patients with positive HER2 conversion the mOS is 90 m. and for the patients with negative HER2 conversion the mOS is 21 m. (p value=0.008).
The patients with metastatic BC and positive HER2 conversion have significantly higher mOS than the patients with metastatic disease and negative HER2 conversion (p<0.05). The mean duration of anti-HER2 therapy among the patients with metastatic disease and positive HER2 conversion is 31.1 m. which may contribute to the improved mOS in this population.
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