Aim: Primary objective was to determine the discordance rates in hormonal receptors (estrogen, progesterone receptors) and HER2 between primary breast cancer and matched locoregional or systemic recurrences in Egyptian patients, while secondary objective was to compare the disease free survival in patients with and without receptors discordance. Methods: 62 patients with recurrent breast cancer (47 locoregional and 15 distant metastases) were recruited from Ain Shams University Clinical Oncology Department, assessment of hormonal receptors (ER and PR) and HER2 status were done for both primary tumor specimens and corresponding specimens of recurrences using immunohistochemistry, with hormonal receptors positivity defined as equal or more than 1% of tumor cell nuclei staining positively, HER2 positive defined as IHC score (3 +) and negative results is either score (0 or 1+), if HER2 status is equivocal (2+) biopsies will be retested for HER2 oncogene by (FISH), effect of adjuvant therapy on receptors discordance was also evaluated, disease free survival (DFS) was compared in patients with and without receptors discordance, the change in treatment decision was assessed by documentation of treatment decision before and after biopsy results. Results: Discordance rate of ER was 22.6% with statistically significant difference between ER of primary tumors and ER of recurrences (McNemar's test p = 0.029), discordance rate of PR was 33.9%, also with significant difference ( p = 0.027), HER2 discordance rate was 11.3% with non-significant difference ( p = 0.45), with an overall discordance rate of 38.7%, effect of adjuvant therapy on receptors discordance demonstrated a statistically significant effect of adjuvant hormonal therapy in down regulation of the ER and PR from the tumor cells throughout disease progression ( p = 0.008), there was non-significant difference between DFS of the discordant group and the concordant group (26.5 months vs. 30.5 months) p = 0.4, as a results of re-biopsy from recurrent disease treatment decision was changed in 17.7%. Conclusions: We have shown a statistically significant discordance rates in hormonal receptors (ER and PR) between primary and recurrent breast cancer, and a change in treatment decision in a considerable number of patients, these findings prompt consideration of re-biopsy from recurrent tumors. Disclosure: All authors have declared no conflicts of interest.

Background: Breast cancer is the most common cancer diagnosed worldwide, synchronous bilateral breast cancer accounts for unique entity of the disease, particularly post-operative radiotherapy for Synchronous Bilateral Breast Cancer (SBBC) is challenging with lack of evidence about the best irradiation technique. In this study, we tried to explore the optimum radiotherapy technique regarding the dosimetric parameters. Methods: We recruited 15 SBBC patients in whom post-operative radiotherapy was indicated and we established three plans for each patient using 3DCRT, IMRT and VMAT, and then we compared the three plans as regard target volume coverage parameters and organs at risk (OAR) doses. Results: We found that PTV coverage parameter was superior with IMRT compared with 3DCRT and VMAT in terms of Dmean (p = 0.001), D95% (p = 0.001), D max (p = 0.0001), conformity index (p = 0.0001) and HI (p = 0.0001). Doses to OAR were not significantly different between the three techniques in cardiac dose and LAD maximum dose, but 3DCRT was superior in LAD mean dose (p = 0.03) and lung volume receiving 20 Gy (V20) and 10 Gy (V10) (p = 0.0001), but this difference was non-significant between 3DCRT and IMRT (p = 0.4 and 0.06 respectively), while VMAT led to the highest doses to LAD and lung. Conclusions: IMRT showed the best target coverage parameters in post-operative radiotherapy for SBBC compared with 3DCRT and VMAT. For OAR doses IMRT showed comparable results with 3DCRT, while VMAT delivered a significantly higher dose to OAR.