Prognostic value of immunohistochemical phenotypes (IP) of 141 operable breast cancer patients (pts) included in phase III trials of adjuvant therapy
21040 Background: Gene expression arrays and IP studies classified breast cancer in three distinct subtypes: basal, HER2/neu and luminal that are associated with different clinical outcomes. Methods: In 141 pts with operable breast cancer, included in phase III trials of adjuvant therapy in our center, immunohistochemical staining was performed on 3μm sections of paraffin blocks, containing tissue-arrays of tumour tissue.A basal phenotype (BP) was defined by negative estrogen receptor (ER) and progesterone receptor (PR) and positive cytokeratin (CK) 5/6 or EGFR immunoreactivity. HER2/neu phenotype as positive c-erb B2 by HercepTest™ and luminal phenotype (LP) by positive ER, PR and CK 7/8 and negative HER-2. Survival curves were calculated by the Kaplan-Meier method. The differences between survivals were estimated using the log rank test. Multivariate Cox regression analysis was used to evaluate any independent prognostic effect of the variables on disease-free survival (DFS). Results: Complete clinical follow-up information was available for 141 pts. The median follow-up period was 52 months (range 1–103 months). During this period, 13.8% pts died from breast cancer and 27.7% pts relapsed. At the time of the primary diagnosis 10.4% of the pts had lymph node negative disease and 89.6% had positive lymph nodes. 50.8% pts received taxane chemotherapy, 7.7% Trastuzumab, 62.3% radiotherapy and 61% pts received hormonotherapy. Positivity for LP was 65.2%, BP 9.9% and Her-2 phenotype 8.5%. 16.3% didn't fit for any of the three subtypes. Median DFS for BP: 24 moths, for LP and Her-2 phenotypes median DFS was not reached. 5 years DFS were; BP: 19%, LP: 63% and Her-2: 56%. Kaplan-Meier survival analyses demonstrated that the presence of a detectable BP was highly significantly associated with a worse DFS compared with the presence of a LP, log rank test (p= 0.0001). Multivariate Cox regression analyses estimated that the prognostic effect of BP in relation to DFS was independent of lymph node, stage and tumor size, HR: 0.12 95% CI (0.05–0.2). Conclusions: We found that expression of BP was associated with poor prognostic in the context of randomized phase III trials. No significant financial relationships to disclose.