Circulating Tumor Cells and Chemo
A typical cancerous tumor contains millions or even billions of cells harboring genetic mutations driving them to grow, divide, and invade the local tissue in which they’re embedded. However, as the cells proliferate, they don’t all stay in the neighborhood. Some cells slough off the edges of a tumor and are swept away by the bloodstream or lymphatic system. These so-called circulating tumor cells (CTCs) can remain loose in circulation, cluster together as they travel, or lodge themselves in new tissues. Whatever their path, their common origin means that CTCs hold information about a tumor, information that researchers think could be key to cancer diagnosis or treatment.
Cancer patients have only between 5 and 50 CTCs per teaspoon of blood, so their presence is dwarfed by blood cells. However, in the past decade emerging technologies have, for the first time, allowed the isolation of CTCs from patients’ blood samples. Some methods, among the first established, rely on the cells’ physical properties. When a blood sample settles or is spun in a centrifuge, red blood cells, white blood cells, and other components of blood separate into layers. Based on their buoyancy, CTCs can be found in the white blood cell fraction. Then, because CTCs are generally larger than white blood cells, a size-based filter can divide the cell types.
- Everyone with cancer has CTCs!
- CTCs are NOT yet rapidly replicating
- Therefore CTCs are NOT killed by chemotherapy
- CTCs are ONLY kept dormant by a healthy immune system
- Chemotherapy and radiation greatly inhibit the immune system
- Therefore Chemotherapy and radiation greatly increase metastatic risk
In 1869, pathologist Thomas Ashworth noticed some unusual cells in the blood of a patient who had died of cancer. The cells didn’t look like normal blood cells; instead, they were similar in appearance to those found in the numerous solid tumors present all over the patient’s body. Ashworth speculated that perhaps the cells were derived from the existing tumors, and could help explain the distribution of the patient’s multiple lesions (Australian Med J, 14:146-49, 1869).
Scientists now believe that these so-called circulating tumor cells (CTCs) play a key role in metastasis. Because CTCs can be obtained through routine blood draws—a procedure that is much easier and less invasive than a tumor biopsy, making it amenable to repetition—many scientists are hopeful that the cells could be used to detect cancer and metastases at an early stage. CTCs could also help doctors plot the molecular signature of an individual’s tumor over time, monitor a tumor’s responsiveness to therapy, and identify targets for the development of personalized therapies.
Why they are IGNORED by standard Oncology
However, pharmaceutical research is driven by money. Since the main medical cancer therapies (chemotherapy and radiation) do NOT kill CTCs, the chance of cancer metastasis following chemo and/or radiation greatly increases!
Let's think about it - standard oncology makes their money selling therapies that may kill cancer cells but actually protect circulating tumor cells, setting the patient up for cancer to "come back with a vengeance" within a short period of time. Addressing CTCs may greatly disrupt money flow from standard therapies!
A recent University of Michigan study stated that, "This study confirms the prognostic significance of CTCs in patients with MBC receiving first-line chemotherapy. For patients with persistently increased CTCs after 21 days of first-line chemotherapy, early switching to an alternate cytotoxic therapy was not effective in prolonging OS. For this population, there is a need for more effective treatment than standard chemotherapy." They suggest that for many cancer patients, there is even an INCREASE in CTCs following chemotherapy! For these the study goes on to suggest that there may be a "need for more effective treatment than standard chemotherapy."