A new study just published in the Journal of Clinical Oncology has shown that monitoring the count of circulating tumor cells (CTC) using the CellSearch system from Veridex, a Johnson & Johnson company, can predict the prognosis of patients with metastatic breast cancer. The CellSearch system uses ferrofluid iron microparticles attached to antibodies that like to grab on to CTC cells. Using a magnet, the device can remove the particles out of a blood sample for precise identification and number count.
More about CellSearch and some details about the study from the J&J press release:
CellSearch® test results should be used in conjunction with all clinical information derived from diagnostic tests (e.g., imaging, laboratory tests), physical examination and complete medical history in accordance with appropriate patient management procedures.
A retrospective study was performed on 115 patients with MBC who had the CellSearch test performed as part of their initial staging process at M.D. Anderson over a three-year period. CTC count and FDG-PET/CT imaging were performed at baseline in 102 evaluable patients before starting a new therapy and then again at the midpoint of their therapies (9 – 12 weeks). Patients outcomes were categorized according to midtherapy CTC counts as favorable (< five CTCs/7.5 mL blood) or unfavorable (≥ five CTCs/7.5 mL blood). Based on FDG-PET/CT, patients were considered responders if metabolic activity of target lesions decreased more than 25% compared to baseline, and if there was no change or a decrease in size. Patients were considered nonresponders if the FDG uptake was similar or higher and/or if target lesions had increased in size. CTC counts and FDG-PET/CT response at midtherapy were compared, and univariate and multivariate analyses were performed to identify factors associated with survival.
A total of 115 patients with metastatic breast cancer were considered for the study and 102 were evaluable for efficacy. The median overall survival time was 14 months (range, 1 to > 41 months). In univariate analysis, both midtherapy CTC counts and FDG-PET/CT response predicated overall patient survival (p<.001 and p=.001, respectively). The overall concordance between the CTC counts at midtherapy and FDG-PET/CT was 67% for response/nonresponse and 74% for progression/nonprogression. In the discordant category, detection of five or more CTCs during therapeutic monitoring accurately predicted prognosis in MBC beyond metabolic response. FDG-PET/CT was able to predict outcome in discordant instances of patients with less than five CTCs at midtherapy. Midtherapy CTC levels remained significant in a multivariate analysis (p=.004). These results suggest a higher and independent predictive value of CTCs compared with FDG-PET/CT among patients with a CTC count of five or more. In addition, there was a strong correlation between complete response and the absence of significant levels of CTCs (median CTC level zero).
Press release: Monitoring Circulating Tumor Cells with the Cellsearch® System Can Predict Prognosis in Metastatic Breast Cancer…
Abstract in Journal of Clinical Oncology: Circulating Tumor Cells and [18F]Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Outcome Prediction in Metastatic Breast Cancer
Product page: CellSearch Circulating Tumor Cell (CTC) Kit…