P4-07-10: Circulating Tumor Cells in Newly Diagnosed Inflammatory Breast Cancer.

Abstract

Abstract Background: Inflammatory breast cancer (IBC) is one of the most aggressive forms of breast cancer and is associated with special clinical and biological features. Circulating tumor cells (CTC) are an independent prognostic factor in metastatic breast cancer for progression-free and overall survival. Previously we showed that metastatic IBC patients treated with first and subsequent lines of chemotherapy had a lower number of CTC when compared with CTC levels of non-IBC patients; hence the prognostic value of CTC in mIBC patients is limited. In the present study, we investigated the prognostic value of baseline CTC in newly diagnosed IBC patients. Patients and methods: This retrospective study included 84 newly diagnosed IBC (37 stage III B or C and 47 stage IV) patients treated with neoadjuvant therapy or first line chemotherapy between January 2004 and July 2009 at the MD Anderson Cancer Center. The median age was 55 years (range, 23–78). Twenty-four (28.8%) patients were HER2 positive, 36 (42.9%) hormone receptor positive and 33 (39.3%) were triple receptor negative. CTC were detected and enumerated using the CellSearch® system before patients started chemotherapy. Progression free survival (PFS) and overall survival (OS) were calculated from the date of CTC measurement and estimated by the Kaplan-Meier product limit method. Results: At baseline, 64 (76.2%) patients had at least ≥1 CTC and 29 (34.5%) ≥5 CTC. Proportions of patients with stage III IBC with ≥1 CTC and ≥5 CTC were lower than those of newly diagnosed stage IV IBC patients (67.6% vs. 86%; p = 0.12 and 24.3% vs. 42.6%; p = 0.11, respectively). At a median follow up of 22.4 months (range: 4.8 - 58.3 months), 48 (57.1%) patients experienced disease progression and 26 (31.0%) had died. Patients with < 5 CTC had similar PFS (p = 0.36) and OS (p = 0.80) to those of patients with ≥5 CTC, respectively. We investigated the prognostic value of CTC ≥ 1 in stage III IBC patients, as well. There was no difference in PFS (p = 0.71) and OS (p = 0.15) in patients with CTC = 0 vs. those of patients with CTC ≥ 1, respectively. Moreover, we correlated CTC levels with prognosis, using different CTC threshold, but we observed no correlation between baseline CTC and patients’ outcome (Table 1). Conclusions: CTC can be detected in a large proportion of patients with newly diagnosed IBC; however, baseline CTC was not prognostic for PFS and OS. Collective dissemination of cancer cells via lymphovascular tumor emboli and/or epithelial-mesenchymal transition accompanied by inadequate detection of CTC due to lack of sensitivity of current assays may account for limited prognostic value of CTC in newly diagnosed IBC. Nevertheless, sample size and study power could influence study results as well. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-10.