CT-DNA (Circulating Tumor DNA Test)

Most people with cancer have DNA derived from cancer cells circulating in their blood. In this Circulating Tumor DNA (CT-DNA) gene variants can occur that cause the tumor.

The CT-DNA test (also referred to as Liquid Biopsy) can be used in the follow-up of a patient-specific cancer treatment with designer molecules (personalized medicine).

The CT-DNA test can also diagnose many tumors in an early stage and is therefore recommended for people with an elevated risk to develop cancer.

GENDIA’s CT-DNA test detects +/- 2800 common gene variants in 50 oncogenes that cause many tumors (see Table 1).

The 50 cancer genes analysed in this test are (in alphabetical order): ABL1, AKT1, ALK, APC, ATM, BRAF, CDH1, CDKN2A, CSF1R, CTNNB1, EGFR, ERBB2, ERBB4, EZH2, FBXW7, FGFR1, FGFR2, FGFR3, FLT3, GNA11, GNAQ, GNAS, HNF1A, HRAS, IDH1, IDH2, JAK2, JAK3, KDR, KIT, KRAS, MET, MLH1, MPL, NOTCH1, NPM1, NRAS, PDGFRA, PIK3CA, PTEN, PTPN11, RB1, RET, SMAD4, SMARCB1, SMO, SRC, STK11, TP53, VHL.

Table 1: Frequency of gene variants in different cancers (%)


There are 2 important indications for a CT-DNA test:

  • Patients undergoing cancer treatment:
    1. To identify the mutation(s) that cause the cancer, and to select a patient-specific treatment with designer molecules (personalized medicine)
    2. To detect resistance against the cancer treatment as a result of new or previously undetected oncogenic gene variants
    3. To detect metastases
  • Patients with an elevated risk on cancer : Carriers of a gene variant that predisposes to cancer (mainly breast, ovarian, colon or uterine cancer) can be screened periodically (mostly 1x/year) with the CT-DNA test to detect cancer in an early stage.

The CT-DNA test is performed on blood in a special kit that can be requested from GENDIA in Antwerp. The kit can be returned at room temperature to GENDIA (Emiel Vloorsstraat 9, 2020, Antwerp, Belgium).

The CT-DNA test takes 1 month counting from the arrival of the sample at GENDIA to the reporting of the result.

Circulating tumor DNA (CT-DNA) from blood is tested for +/- 2800 gene variants in 50 cancer genes (oncogenes) (table 1). The CT-DNA test is performed in the USA under CLIA accreditation.

The results will be mailed to you personally by e-mail.
If you want your physician or others to get a copy, you can indicate so on the form.

There are 2 possible results with the CT-DNA test:

  1. A gene variant is found with the CT-DNA test: Such gene variant only occurs in cancer cells. This does not mean you have cancer or are certain to develop cancer in the future. It’s possible that a tiny amount of CT-DNA circulates in the blood but no tumor is formed yet. It is important to discuss the results with the GENDIA physician, your own physician and an oncologist and set up a personalized cancer screening program to rule out the existence of cancer.
  2. No gene variant is found with the CT-DNA test: In that case there is no indication that cancer is currently present in your body.

The CT-DNA test cannot detect all cancers for various reasons: some cancers are too small so the amount of CT-DNA is too limited to get detected by the CT-DNA test. Cancers caused by gene variants other than the 2800 gene variants screened by the CT-DNA test will not be picked up.

Finding a gene variant with the CT-DNA test does not always mean that a tumor is present. Sometimes a tiny amount of CT-DNA circulates in the blood but no tumor is formed yet.

Your sample and DNA will be used for the CT-DNA test only. Your DNA will be kept in the laboratory. The results of the CT-DNA test will be kept at GENDIA and in the laboratory.

GENDIA will meet Belgian and EU legislation and regulations concerning the protection and privacy of personal data and the collection, use, processing, saving and storing of patient data.

The results of the CT-DNA test will only be reported to you, not to any third party, including family members, insurance companies or physicians, unless requested by you.

A consultation with genetic advice and explanation of the test is recommended before taking the test.

You can make an appointment with your own physician or with the GENDIA physician through info@gendia.net.

Samples can be sent to GENDIA through express mail.

When a gene variant is found that might indicate the existence of cancer cells, a consultation with your own physician or with the GENDIA physician is highly recommended in order to set up a personalized cancer screening and possibly treatment plan.

You can make an appointment with GENDIA through info@gendia.net.

You can request a CT-DNA Test through your own physician or GENDIA.

The necessary forms can be requested through info@gendia.net.

Also see: Order a CT-DNA test

The price of the CT-DNA test is 690 Euro.

See also: Prices and Payment

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