Circulating tumor cells (CTCs) are cells that have detached from a primary tumor and circulate in the bloodstream. CTCs may travel to other areas and create new tumors in different tissues or organs (metastatic). Elevated CTCs at any time in the course of clinical treatment of metastatic cancer are indicators of progression.
WHY IS IT IMPORTANT TO TEST FOR CTCS?
The capture and detection of CTCs may have important prognostic and therapeutic implications, primarily because detection of tumor cells assists in early detection of relapse and in monitoring the response to treatment. The presence of tumor cells circulating in the blood is associated with shortened survival from various solid tumor cancers.
I HAVE BEEN DIAGNOSED WITH CANCER AND WILL SOON BEGIN TREATMENT. HOW IS CTC TESTING USEFUL TO ME?
If you have just been diagnosed with cancer, the optimal time to test the CTCs is prior to treatment (providing a baseline CTC count) and part way through treatment to determine if the CTC count is declining (indicating response to treatment).
In other words, the CTC count is a predictive indicator, in that it predicts response to treatment. If the CTC count rises, it indicates the cancer is not responding to the chosen treatment.
This provides your doctor with information that can help guide treatment planning and change your treatment(s) sooner if needed. It is also helpful to test the CTCs at the end of treatment, to determine the presence or absence of CTCs. The CTC count after treatment serves as a prognostic indictor (i.e. cancer-specific survival and risk for recurrence).