What is circulating tumor cell test?
Circulating tumor cell (CTC) count identifies and quantifies the EpCAM protein produced by epithelial tumor cells. Testing should be done prior to the initiation of therapy and serially during treatment. CTC count may also aid in determining prognosis and in assessing treatment efficacy.
How CTCs are formed?
In metastatic disease, CTCs are postulated to be derived from both the primary and metastatic lesions and, in the case when the primary has been resected, only from the metastatic lesions. Metachronous metastases are common in breast cancer, prostate cancer, colon cancer, and melanoma.
What is the difference between cell free DNA and circulating tumor DNA?
When a cell dies, it releases cell free DNA (cfDNA) into the bloodstream. cfDNA is a term that broadly describes the different types of DNA freely circulating in the bloodstream at any given time. This includes circulating tumor DNA (ctDNA), which is released when tumor cells die.
What is the difference between CTC and ctDNA?
From our point of view, ctDNA analysis should be chosen for analysis of mutations, copy number aberrations, and DNA methylation changes, whereas CTC analysis provides the unique opportunity to study whole cells, thus allowing DNA, RNA, and protein-based molecular profiling, as well as use in vivo studies.
Why is it challenging to collect and analyze CTCs?
However, due to a limited captured number of CTCs in most cancer types, it is difficult to analyze the SNV evolutionary structure in individual patients. Moreover, copy number variation (CNV) is also frequently altered during cancer evolution.
What does negative ctDNA mean?
A decrease in the quantity of ctDNA suggests the tumor is shrinking and treatment is successful. Monitoring periods with no symptoms (remission of cancer). A lack of ctDNA in the bloodstream indicates that the cancer has not returned.
What is the role of cell free circulating tumor DNA testing?
Diagnosing the type of tumor using ctDNA can reduce the need for getting a sample of the tumor tissue (tumor biopsy), which can be challenging when a tumor is difficult to access, such as a tumor in the brain or lung. Guiding tumor-specific treatment.
How is cfDNA collected and isolated?
A commonly used column-based method to isolate cfDNA from plasma and serum is Qiagen’s QIAamp circulating nucleic acid kit (Qiagen, Hilden, Germany) [7,8]. The Qiagen cfDNA method involves initial plasma separation using centrifugation and subsequent column-based extraction.
How do you differentiate between ctDNA and cfDNA?
cfDNA is a fragment of DNA released into the plasma after cell apoptosis by lysis, which carries genome-wide DNA information. ctDNA is a part of cfDNA, which can be derived from primary tumors and metastases, even circulating tumor cells (CTC).