92 Background: Estrogen receptor (ER), progesterone receptor (PgR), and HER2 status are important biological markers for making decisions about breast cancer treatments. Although changes of hormone receptor (HR) and HER2 status with recurrence of breast cancer are clinically experienced, the frequency of discordance and clinical significance are still unknown. Thus, we investigated ER, PgR, and HER2 status with primary tumors and recurrent lesions, and assessed discordance rates and prognosis. Methods: We retrospectively identified recurrent breast cancer patients who had biopsies or resections of recurrent lesions between January 2007 to April 2012 at Keio University Hospital. HR status was assessed by immunohistochemistry (IHC) and determined using the Allred score. HR status was defined as positive when score was 3 and more. HER2 status was assessed by IHC and fluorescence in situ hybridization (FISH) analysis. We defined HER2 positivity as 3+ staining intensity by IHC or the presence of HER2 gene amplification by FISH. Results: Among 32 recurrences, 40% (13) were loco-regional recurrences (LLR) and 60% (19) were distant metastases (DM) (lung 14; liver 3; brain 1; pleura 1). Discordance rates in ER, PgR and HER2 status between the primary tumors and the recurrence lesions were 12.5%, 31.3%, and 13.8%, respectively. The most common change was loss of PgR. Changings from negative to positive in ER, PgR and HER2 status were found in 6.3%, 3.1%, and 3.4% of the patients, respectively. All gains were found in distant metastases. Discordance in ER and HER2 were more common in DM (15.8% and 17.6%) comparing with LRR (7.7% and 8.3%). Loss of HR status was not associated with a shorter time to progression (TTP) (ER: 19.3 vs. 8.5 months, p=0.185; PgR: 4.4 vs. 11.5 months, p=0.907). Patients with discordant HER2 status had significantly shorter TTP than with concordant status (0.9 vs. 11.5 months, p=0.012). Conclusions: Discordance of biological markers between primary and recurrent breast cancers were seen in 10-30%. Although HR discordance was not associated with prognosis, patients with HER2 discordance had poorer TTP. Tissue confirmation should be considered for making effective treatment decisions in recurrent breast cancer.
PO113 DISCORDANCE OF HORMONE RECEPTOR AND HER2 STATUS BETWEEN PRIMARY AND RECURRENT BREAST CANCER: NEW TREATMENT STRATEGY FOR PREDICTING OUTCOME OF PATIENTS WITH BREAST CANCER
