CTCs were first discovered in 1869 – yes, that long ago! Their critical role in the progression of cancer to metastasis is undisputable. However, CTCs are rare – there may only be a single CTC amongst millions of blood cells. The establishment of a reliable means of detecting them has taken decades, and it is only with recent technology advances that it has been possible to achieve.
Very early in tumour development, the tumour may send out some extremely sneaky cells into the bloodstream. The cells may circulate in the bloodstream as dormant cancer cells for months or years, and may even survive cancer treatment aimed at treating a primary cancer. The cells are called Circulating Tumour Cells, and are the cause of cancer spread, metastases. It is the metastases, rather than the primary tumour, which is most often responsible for patient fatality. Circulating Tumour Cells have become a hot topic in cancer research laboratories and Oncology conferences worldwide: if these cells can be targeted, then it is possible to stop cancer in its tracks.
Circulating Tumour Cells, abbreviated as ‘CTCs,’ were first discovered over 150 years ago. The reason that it has taken so long for CTCs to become the focus of much research attention is because they it has been near impossible to develop a reliable way of detecting them. You see, CTCs are incredibly rare. There may be one CTC in amongst millions of blood cells. It has been only recently that scientist have been able to develop methods of finding, counting and analysing these cells.
A popular method is to separate CTCs based on their biological properties. Epithelial-derived cancers (breast, prostate, lung, liver, skin, oral, colorectal) will have molecule called EpCAM on the surface of their cells. Immunomagnetic cell enrichment finds CTCs via magnetic-bound anti-EpCAM antibodies. This sounds complex, but it’s really not. Basically an antibody is a molecule that attaches specifically to things. This one is made to specifically attach to the molecule EpCAM that is found on the outside of CTCs.
One technology that has been critically acclaimed is Maintrac, from Germany. Maintrac detects cells via their cell surface receptor EpCAM. However, instead of using magnetic-bead bound antibodies, they use antibodies labelled with a fluorochrome bead. When this antibody binds to an EpCAM on the surface of a CTC, it fluoresces.
Maintrac technology has been clinically validated and published in peer-review journals for over twelve years. Maintrac tests are acknowledged and utilised by many universities, Oncologists and cancer clinics worldwide.