Circulating Tumor Cells for Assessing Survival in Pancreatic Cancer Patients

I believe that a new chapter in the history of cancer diagnosis is now being written through the analysis of circulating tumor cells (CTSs) and their comparison with cells of the primary malignant lesion. A summary of a recent research article provides a fitting prologue for the discussion here (see: Circulating tumour cells tied to poorer survival in pancreatic cancer sufferers), Below is an excerpt from it:

Circulating tumour cells are associated with poorer survival in pancreatic cancer patients, a new American research has found. The study  conducted by researchers at the Fox Chase Cancer Center, also uncovered evidence that not all circulating tumour cells are the same, and some may predict worse outcomes than others....Previous work has demonstrated that prostate, colon, or breast cancer patients who have more circulating tumour cells have poorer survival than patients with fewer circulating tumour cells. To learn whether a similar scenario occurs in pancreatic cancer patients, [the authors of the study] enrolled 48 patients with pancreatic cancer in the current study ....The team used an immunomagnetic separation system to isolate circulating tumour cells from patients'' blood at three time points. The time points included study entry, seven days after the start of therapy, and at the time of their first radiological evaluation, which was six to ten weeks after initiating therapy. The team found that 50 per cent of the patients had one or more circulating tumour cell per 7.5 mL peripheral blood at baseline. That proportion decreased to 40 per cent after seven days of therapy and to 32 per cent at the time of the first scan. Moreover, the presence of circulating tumour cells correlated with patient outcomes. Patients with circulating tumour cells at study entry had a median overall survival of 191 days compared with 269 days for those without circulating tumour cells, although the difference did not reach statistical significance in the small study population....Interestingly, the investigators found that some circulating tumour cells may be worse than others. Patients whose circulating tumour cells expressed the MUC1 protein, which has been associated with more aggressive pancreatic cancer, trended towards a shorter median overall survival than those whose circulating tumour cells did not express the protein, at 85.5 and 310 days, respectively.

It will come as no surprise that cancer patients with circulating tumor cells have a worse prognosis than those that do not. Moreover and as noted above, not all CTCs have equal prognostic significance. Patients whose CTCs expressed MUC1 protein had a shorter median overall survival. The cell membrane mucin MUC1 is over-expressed and aberrantly  glycosylated in many cancers (see: Identification of a novel cancer-specific immunodominant glycopeptide epitope in the MUC1 tandem repeat),

Clearly, both quantitative and qualitative analysis of CTCs will be of great value in assessing both the prognosis of cancer patient as well as the ongoing efficacy of therapy. This will allow rapid switches in the chemotherapy regimen similar to that enabled by slight tumor shrinkage viewed by medical imaging. We now are entering an era where we can isolate tumor cells from the peripheral blood inexpensively and with relative efficiency. Note he reference above to the use of an "immunomagnetic separation system. I posted a previous note about use use of a microchip to achieve this same goal (see: Microchip Separation of Circulating Tumor Cells as a New Cytopathology Technique),

The CellSearch test from Veridex is a commercially available system for assessing CTC status. Here's a list of summary points about the CellSearch CTC test copied from the Quest Diagnostics web site:

• Immunomagnetic cell enrichment using antibodies targeting epithelial cell adhesion molecule (EpCAM) and nucleus labeling with fluorescent dye
• Epithelial cells distinguished from leukocytes using fluorescent-labeled monoclonal antibodies specific for epithelial cells (cytokeratins 8,18, and 19) and leukocytes (CD45)
• Results reported as number of CTCs/7.5 mL whole blood
• Analytical sensitivity: 1 CTC/7.5 mL whole blood

Comments

[Personalized Cancer Therapy]

Thank you for this information, much more research is needed on the Circulating tumour cells in order to learn the exact behaviour and how it is affect patient survival, we need to put as much effort as we can in research.