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Background. The Oncotype DX recurrence score (RS) assay has been validated for prediction of 10-year risk of distant recurrence and likelihood of benefit from chemotherapy in patients with estrogen receptor (ER)-positive, HER2-negative early breast cancer. Patients with high RS tumors have substantial benefit, and patients with low RS tumors have minimal if any benefit from chemotherapy. Tumor size is used as a key parameter when selecting patients for neoadjuvant chemotherapy. The aim of this study was to assess the distribution of RS in patients selected for neoadjuvant chemotherapy primarily according to tumor size. Patients and Methods. Patients with ER-positive and HER2-negative tumors that were node-negative or had no more than 1 positive node from three trials were included in this study. Oncotype DX was performed at Genomic Health, Inc., blinded to the clinical data. Descriptive statistics were calculated for distribution of RS for all cases. Results. Of 277 patients, 96 met eligibility criteria, and 81 had sufficient material for analysis. Median tumor size was 40 mm (interquartile range [IQR], 30–50 mm). Grade I, II, and III were observed in 13, 49, and 17 cases, respectively. There was a wide distribution of RS with a median of 21.4 (IQR, 16.05-26.75). In total, 23 (28.3%) had high, 28 (34.6%) intermediate, and 30 (37%) low RS results. Conclusion. The RS may provide relevant information for neoadjuvant treatment decisions in select patients both in clinical practice and in studies. Inclusion of low RS disease patients in neoadjuvant trials will likely only dilute the ability to look at treatment effects.

Background. The primary aim of this retrospective study was to investigate intraindividual correlation of estrogen receptor (ER) status, progesterone receptor (PR) status, and HER2 status between primary breast cancer and metastatic breast cancer (mBC). Secondary aims included patients' characteristics, overall survival, feasibility of histopathological evaluation in the metastatic setting, and predictive factors associated with receptors status discordance. Methods. Patients with either biopsy of metastatic relapse or surgery of metastasis were identified. Demographics, tumor characteristics, treatment characteristics, and ER, PR, and HER2 statuses were retrospectively obtained in patients' reports. Receptors statuses were assessed by immunohistochemistry with a positivity cutoff of more than 10% for ER and PR. HER2 was considered as positive if overexpression was scored at 3+ in immunohistochemistry or if amplification ratio was >2 in fluorescent in situ hybridization. Results. From a cohort of 489 patients with mBC, 269 patients had histopathological samples of metastatic relapse. Histopathological analysis of the specimen confirmed the diagnosis of mBC in 235 patients. Discordance in one or more receptors between primary breast cancer and mBC was found in 99 patients (42%). A switch in receptor status was identified for ER in 17% of tumors (p = 4 × 10−3), PR in 29% of cancers (p < 4 × 10−4), and HER2 in 4% of lesions (p = .16). Exposure to chemotherapy and to anthracycline-based chemotherapy was statistically associated with switches in ER status. Seven (2%) second malignancies and three benign diseases (1%) were diagnosed. Conclusions. This study confirms that discordance in ER and PR receptor expression between the primary breast tumor and the corresponding metastatic lesions is high, whereas HER2 status remains relatively constant. Chemotherapy, and specifically anthracycline-based chemotherapy, was associated with switch in ER status. These results were obtained in a selected population of patients; further studies are warranted to confirm these data and to determine the interest of systematic rebiopsy in the metastatic setting.