CTC
Meaning of CTC: The scan can find a growth but cannot remove or sample one, so anything suspicious still ends in a scope procedure.
Definition of CTC
CTC most often stands for computed tomographic colonography, a CT scan processed by computer into two and three dimensional views of the inside of the colon. Because nothing enters the bowel except a thin tube used to inflate it with gas, it is also called virtual colonoscopy. In oncology the same three letters mean circulating tumor cell.
How is the examination done?
The bowel is cleared beforehand with a preparation, because material left behind can mimic a growth on the images. A thin tube in the rectum then inflates the colon with carbon dioxide so its walls separate and the lining can be seen. Scans are taken with the person lying face up and face down, which shifts any remaining fluid and helps separate it from a genuine finding. A radiologist reviews the reconstruction on a computer, able to rotate the view or travel along the inside of the bowel as though passing through it. No sedation is used, so there is no recovery period afterward.
How does it compare with a standard colonoscopy?
| CTC | Colonoscopy | |
|---|---|---|
| Bowel preparation | Required | Required |
| Sedation | Not used | Usually used |
| Tissue sampling | Not possible | Polyps removed and biopsies taken during the same procedure |
| Radiation | Involves x-rays | None |
| Findings outside the colon | Frequently seen, useful and unhelpful alike | Not assessed |
The trade is straightforward. CT colonography is quicker and avoids sedation and instrumentation of the bowel, which suits someone who cannot tolerate or complete a scope examination. It cannot treat what it finds, so a suspicious area in screening for colon cancer means a second appointment for a scope.
What else does CTC stand for?
A circulating tumor cell is a cancer cell that has broken away from a tumor and entered the bloodstream. Such cells are rare among the vast number of blood cells, and specialized techniques are needed to capture and count them from an ordinary blood sample, which is why they are studied as a way of following a cancer without repeating a tissue biopsy. In older oncology writing the same letters also stood for Common Toxicity Criteria, the graded scale for describing side effects, now published under the name CTCAE.
Also known as
Used in a sentence
CTC was performed to evaluate the colon after the patient was unable to tolerate a standard colonoscopy.
Good to know
CTC can identify a suspicious area inside the colon but cannot sample tissue, so a positive finding is followed by a scope based procedure capable of taking a biopsy.