The RGCC Test Explained: The Greek Blood Test for Cancer Cells and Natural Compounds

The RGCC test, often called the Greek test, is a blood test from the Research Genetic Cancer Centre laboratory in Florina, in northern Greece. It looks for circulating tumor cells, living cancer cells that have broken away from a tumor and travel in the blood, and then tests those cells against chemotherapy drugs, targeted drugs and natural substances. It is one of the most widely used tests in integrative oncology, and one of the most misunderstood. This article explains what each RGCC test measures, how the results are used, what the published studies show, and where the test fits alongside standard testing.

Part of our guide: Advanced Cancer Testing: A Guide to the Tests Beyond Standard Scans

Cancer Expert MD has no financial relationship with RGCC or any other laboratory and receives nothing for referrals.

How the RGCC Test Works

Blood is drawn locally into special tubes and shipped by courier to the laboratory. There, the white blood cells are removed and the rare remaining cancer cells are identified by markers on their surface. Because the cells are still alive when they arrive, the laboratory can count them, measure which cancer-related genes they are using, and grow them briefly in culture so they can be exposed to different drugs and natural substances. The report then shows how strongly each agent killed that patient’s cancer cells in the laboratory.

Living cells must reach the laboratory within a few days, so blood is drawn early in the week to avoid weekend delays. The laboratory’s own research describes a storage method that keeps the cells usable for up to 96 hours after the blood draw.¹

The Main RGCC Tests

Oncocount counts the circulating tumor cells in the blood. It is used mainly as a follow-up test, repeated over time to see whether the count is rising or falling.

Oncotrace counts the cells and adds markers that describe them, including markers of cancer stem cells and markers that can suggest where the cells came from. It is used both as a starting test and for follow-up.

Oncotrail is a version tailored to one type of cancer, such as breast, prostate, colon, lung, melanoma or sarcoma, using the markers most relevant to that cancer.

Onconomics tests the patient’s cancer cells against chemotherapy and targeted drugs, and reports the activity of tumor-related genes that may point to further treatment targets.

Onconomics Extracts tests the cells against natural substances only.

Onconomics Plus combines both: more than 50 chemotherapy drugs, targeted drugs, and about 50 natural substances in a single test. It is the most comprehensive panel and is commonly used as the starting test.

Testing Natural Substances Against Your Own Cancer Cells

What sets RGCC apart is the natural substance panel. It tests compounds such as medicinal mushroom extracts, curcumin, vitamin C and other plant extracts directly against the patient’s own circulating cancer cells. Almost no other laboratory offers this. For people using integrative therapies alongside treatment, it adds information that no standard test provides. Our guide to natural compounds and cancer explains the human research behind many of the substances on the panel, including curcumin, medicinal mushrooms and high-dose IV vitamin C.

What the Published Studies Show

The Italian colorectal cancer study. The most detailed study comes from the University of L’Aquila in Italy, working with the RGCC laboratory. It looked back at 36 patients whose colorectal cancer had recurred in the pelvis or spread to the liver and was no longer responding to at least two lines of standard chemotherapy. Their drugs were chosen using RGCC testing of their circulating tumor cells and given directly into the artery feeding the tumor, together with targeted drugs. Seventeen patients had a partial response, meaning their tumors shrank by at least 30 percent, 18 had stable disease and one progressed. Nearly all of the patients who responded had been predicted to respond by the test, but the test was much less able to identify in advance who would not respond, and its overall predictive accuracy was 47 percent. The authors described the result as a first benchmark that newer methods should improve on.²

Earlier pilot studies. The same Italian group published smaller pilot studies using RGCC testing to select treatment in recurrent ovarian cancer and in melanoma that had spread within the pelvis.^3,4

What is still missing. No randomized trial has yet compared treatment chosen by RGCC testing with treatment chosen in the usual way. Until such trials are done, the results are best used as one input among several, alongside tumor sequencing, imaging and blood markers. Our article on chemosensitivity testing explains the broader research on testing cancer cells against treatments, including tumor organoids.

Strengths and Limits

Strengths. The test needs only a blood sample, so it can be done when no tumor tissue is available and repeated as often as needed. It tests natural substances and drugs that standard testing never covers. Repeated counts show the trend in circulating tumor cells over time.

Limits. The method captures cells that carry the usual surface markers of carcinoma cells, so cancer cells that have changed form as they spread may be missed, a point the Italian researchers raised themselves.² A drug that kills cells in a dish does not always work as well in the body, where the drug must reach the tumor at a high enough level. Brain tumors generally do not release cells into the blood, so the test is not used for cancers that start in the brain. Counts from one laboratory cannot be compared with counts from another, and the test is generally not covered by insurance in the United States.

How Results Are Used in Practice

Practitioners who use RGCC commonly start with Onconomics Plus, then repeat Oncotrace or Oncocount every three to four months to follow the trend in cell numbers, and repeat the full panel about once a year, because cancer cells change over time and a substance that worked before may stop working. The trend over several tests tells far more than any single count. Our articles on circulating tumor cell testing and cancer testing in Germany and Greece compare RGCC with the other laboratories.

Whether RGCC testing adds useful information depends on the type of cancer, the treatments already used and the other tests available. In a consultation, Dr. Silver, MD, educates you on RGCC and the other advanced tests, what each can and cannot show, and how the results fit together.

How Cancer Expert MD Helps

Cancer Expert MD provides education and consultation for people with every type and stage of cancer, and specializes in Stage IV and metastatic cancer. Our book, The New Reality of Cancer, describes the testing available in each country in detail and how to combine European blood tests with American sequencing and imaging into one monitoring plan. See also our advanced cancer testing guide.

Frequently Asked Questions

What is the RGCC test?

A blood test from a laboratory in Greece that finds circulating tumor cells, counts them, and tests them against chemotherapy drugs, targeted drugs and natural substances.

Why is it called the Greek test?

Because the testing is done at the Research Genetic Cancer Centre laboratory in Florina, Greece.

Which RGCC test is usually done first?

Onconomics Plus is commonly used as the starting test because it combines cell counting, drug testing and natural substance testing. Oncotrace or Oncocount are then used for follow-up.

Is the RGCC test covered by insurance?

Generally not in the United States, so confirm the cost before ordering.

Can the RGCC test be used for lymphoma, leukemia or brain tumors?

The laboratory tests blood cancers such as lymphoma and leukemia. Cancers that start in the brain generally do not release cells into the blood, so the test is not used for them.

About the author. Dr. Silver, MD, graduated from Temple University School of Medicine, completed fellowship training in cardiology, and has practiced medicine for nearly fifty years. A lymphoma survivor of about twenty-five years, he is co-author, with Dr. Lindmeier, DHSc, of The New Reality of Cancer: The Science of Recovery. Read more about Dr. Silver, MD.

Research by Dr. Lindmeier, DHSc, cancer educator and co-author of The New Reality of Cancer.

This article is for general education only and is not individual medical advice. Always consult your own doctor before making any changes to your care.

© 2026 Lovely LYF LLC. All rights reserved. This article draws on the research in The New Reality of Cancer and may not be copied, republished or distributed without written permission.

For more in-depth information on this topic and many others, get our book, The New Reality of Cancer: The Science of Recovery.

Explore our guides: Stage 4 Cancer Options · Advanced Cancer Testing · Integrative Cancer Treatment Options · Natural Compounds and Cancer · Repurposed Drugs for Cancer · Cancer Treatment by Type

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References

1. Apostolou P, Ntanovasilis DA, Papasotiriou I. Evaluation of a simple method for storage of blood samples that enables isolation of circulating tumor cells 96 h after sample collection. Journal of Biological Research (Thessaloniki). 2017;24:11.
2. Guadagni S, Masedu F, Fiorentini G, et al. Circulating tumour cell gene expression and chemosensitivity analyses: predictive accuracy for response to multidisciplinary treatment of patients with unresectable refractory recurrent rectal cancer or unresectable refractory colorectal cancer liver metastases. BMC Cancer. 2022;22:660.
3. Guadagni S, Clementi M, Masedu F, et al. A pilot study of the predictive potential of chemosensitivity and gene expression assays using circulating tumour cells from patients with recurrent ovarian cancer. International Journal of Molecular Sciences. 2020;21(13):4813.
4. Guadagni S, Fiorentini G, Papasotiriou I, et al. Circulating tumour cell liquid biopsy in selecting therapy for recurrent cutaneous melanoma with locoregional pelvic metastases: a pilot study. BMC Research Notes. 2020;13:176.

This article is for education only. It is not medical advice and does not diagnose or treat any condition. Cancer Expert MD has no financial relationship with any laboratory, drug maker, supplement company, clinic or hospital.