Yi et al. BMC Cancer 2010, 10:527 http://www.biomedcentral.com/1471-2407/10/527 Anthracyclines are some of the most widely used and effective drugs to treat patients with breast cancer in the adjuvant setting, as well as for patients with metastatic disease [20-25]. However, cumulative cardiotoxicity is a major limitation to the therapeutic use of anthracyclines and can lead to potentially fatal congestive heart failure [26-28]. Nevertheless anthracyclines are still the most widely used chemotherapeutic agents for the treatment of breast cancer. Because of their wide use and proven efficacy, anthracyclines may be especially important for the treatment of TNBCs that are known to lack specific therapeutic targets. Doxorubicin shows pre-clinical and clinical activity against BRCA1-associated cancers, a clo- sely related group of diseases with significant morpholo- gic, phenotypic, and genetic overlap with TNBCs [29,30]. This further suggests the potential of anthracy- cline chemotherapy as a therapeutic option for TNBCs. Given the interest in using doxorubicin for treating patients with TN tumors, we have retrospectively reviewed the medical records of metastatic breast can- cer patients who received combination chemotherapy with doxorubicin and cyclophosphamide (AC) as a first line treatment. The aim of this study was to evaluate the efficacy of AC combination therapy in patients with TNBC. In addition, we characterized the clinico- pathologic findings relating to the response to AC chemotherapy. Methods Patients We performed a retrospective analysis of medical records of patients with metastatic or recurrent breast cancer who received AC combination chemotherapy as a first-line treatment at Samsung Medical Center between January 2001 and December 2006. These stu- dies were approved by the Samsung Medical Center Institutional Review Board. Immunohistochemistry and molecular classification All pathologic specimens were reviewed by two experi- enced pathologists who determined the status of ER, PgR, and HER2 using immunohistochemical (IHC) tech- niques. According to the Allred scoring system, ER and PgR negativity was defined as a total score from 0-2 by IHC using antibodies to the ER (Immunotech, France) and PgR (Novocastra, UK). According to National Com- prehensive Cancer Network (NCCN) guidelines, HER2 was assessed using IHC techniques (DAKO, Santa Bar- bara, CA, USA) and/or fluorescence in situ hybridization (FISH). IHC grades 0 and 1 were defined as a negative result for HER2, and the lack of HER2 amplification was confirmed by FISH if HER2 was rated 2+ by IHC. “Tri- ple negativity” was defined as a lack of expression of ER, Page 2 of 7 PgR, and HER2. The HER2+ subtype was defined as HER2-positive with ER- and PR-negative, while hor- mone receptor-positive was defined as ER- and/or PR- positive, regardless of HER2-positivity subtypes. Ki-67 growth fractions and p53 status were assessed using antibodies: Ki-67 (DACO, Glostrup, Denmark), and p53 (1:80, Zymed, San Francisco, CA, USA). The percentage of positive nuclei stained for Ki-67 was calculated for each section based on approximately 1,000 carcinoma cell nuclei. High proliferative index was defined as 50% or more stained nuclei. Immunoreactivity of p53 was defined as greater than 5% of cells having distinct nuclear staining. Statistical analysis The treatment response to AC was evaluated by review- ing imaging studies according to the Response Evaluation Criteria in Solid Tumors (RECIST). AC chemotherapy was doxorubicin 60 mg/m2 plus cyclophosphamide 600 mg/m2 every 3 weeks. Progression-free survival (PFS) was defined as the time from the initial date of AC che- motherapy to the date that progressive disease was first documented. Overall survival (OS) was defined as the time from the initial date of AC chemotherapy to the date of death from any cause, or the date of last follow- up. The calculation was performed using the Kaplan- Meier method. The log-rank method (also known as the Mantel-Cox test) was used to compare survival rates. The differences in responses between subtypes were esti- mated by the c2 test or Fisher’s exact test. A p < 0.05 was considered significant. Results Patient cohort Between January 2001 and December 2006, 124 patients with metastatic breast cancer were treated with palliative AC as a first-line treatment at Samsung Medical Center. Immunohistochemical data for ER, PgR, and HER2 sta- tus were available for 110 of these patients. Among them, sixty-eight patients relapsed after surgery for inva- sive breast cancers, and forty-two patients had meta- static diseases at diagnoses. Subgroups were classified on the basis of ER, PR, and HER2 IHC findings with 71 of the 110 patients (64.5%) being HR+, 14 patients (12.7%) HER2+, and 25 patients (22.7%) TN. The median age at diagnosis was 45 years (range, 24-69 years). Median disease free intervals (DFI) after surgery among relapsed patients were 47.6 months for HR+, 40.6 months for HER2+, and 38.7 months for TNBC (p = 0.231). Forty patients (36.4%) were initially diagnosed with metastatic disease. TNBCs showed poorer histologic differentiation (Bloom-Richardson pathologic grade III: 87.5% for TNBC, 25.0% for HER2+,