This guide compares two blood-based cancer assays: the Galleri test and the RGCC test (commonly referred to as the Greek test). It summarizes current knowledge and uncertainties regarding their accuracy, accessibility, and pricing. The objective is to delineate strengths and limitations to assist individuals in evaluating the appropriateness of each test or facilitating informed discussions with healthcare providers.
From Paulette Coates, Functional Medicine Practitioner at Essential Wellness in Colorado:
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Outline
- What are Galleri and RGCC
- Accuracy & Scientific Evidence
- Availability & Use Cases: Who can access them?
- Pricing / Cost
- Appropriate Candidates and Cautions
- Perspectives from the Medical/Clinical Community
- Summary and Considerations
What are Galleri and RGCC
Galleri
- The Galleri test is classified as a multi-cancer early detection (MCED) test. It screens for more than 50 cancer types via a single blood draw by analyzing cell-free DNA (cfDNA) released into the bloodstream by malignant cells. AAFP, Galleri
- Upon identification of a “cancer signal,” the test attempts to localize the most probable tissue or organ of origin, guiding subsequent diagnostic procedures, i.e. imaging or biopsy. Galleri, Hematology-Oncology
- Galleri functions strictly as a screening modality rather than as a diagnostic tool. A positive result necessitates further evaluation, while a negative result does not definitively exclude malignancy.
RGCC (Research Genetics Cancer Center)
- RGCC provides a variety of blood-based oncology tests designed for different clinical purposes, including screening (for asymptomatic individuals) and applications in treatment monitoring, personalized therapeutic decision-making, and circulating tumor cell analysis. RGCC
- Notable RGCC tests include:
- Onco-D-Clare: Early detection for individuals without a cancer diagnosis.
- OncoTrace / OncoCount / OncoTrail: Detection and quantification of circulating tumor or cancer stem cells in patients with suspected or known malignancies.
- Onconomics / Onconomics Plus: Ex vivo evaluation of tumor cell responsiveness to various treatments, supporting personalized therapy selection.
- Thus, RGCC does not offer a universal screening solution but a suite of tests tailored to diverse clinical objectives.
Accuracy & Scientific Evidence
Galleri – Current Knowledge
- Validation studies indicate that Galleri demonstrates high specificity (~99.5%), implying a very low false-positive rate among those without cancer. Healthline
- Its overall sensitivity (ability to detect a cancer signal in affected individuals) is moderate (~51.5% across all studied cancer types), and sensitivity varies by cancer stage (e.g., as low as ~16.8% for stage I cancers, improving in advanced stages). Sermo
- Galleri accurately predicts tissue of origin in approximately 88.7% of cases (within validation cohorts.) However, as not all tumors release detectable cfDNA, negative results cannot guarantee absence of disease. Importantly, the test does not replace standard screenings such as mammography or colonoscopy.
- While increasingly utilized, Galleri has not received U.S. FDA approval as a screening device and is available primarily under laboratory regulations as a commercial test.
Bottom line on accuracy: Galleri shows promise – especially for detecting some cancers, and with high specificity meaning few false-alarms. Sensitivity is limited overall and many early-stage cancers may be undetectable. Also, a positive result is not a diagnosis, but a signal prompting further work-up.
RGCC – Evaluated Evidence
- RGCC reports detection of circulating tumor cells (CTCs), tumor DNA, or related biomarkers, suggesting possible roles in early detection and personalized treatment planning.
- Proposed benefits include non-invasiveness, (just a blood draw), the ability to monitor disease progression or recurrence, and potential for personalized therapy planning. However, critical reviews highlight a lack of robust regulatory approval (e.g., FDA), published validation data, reproducibility, and clinical utility—particularly for asymptomatic screening. Forum Health
- Accordingly, many experts classify RGCC’s offerings as experimental or unproven and advise against using their results as definitive evidence, especially in the absence of established malignancy. Additionally, certain RGCC-related therapies have prompted particular safety and efficacy concerns. Mayo Clinic
Bottom line on accuracy: While RGCC is ambitious in scope (screening, monitoring, therapy guidance), its scientific validation appears limited and insufficient for routine cancer screening. Its clinical benefit is not widely accepted in mainstream oncology.
Availability & Use Cases: Who can access them?
Galleri
- The Galleri test is commercially available in the United States (and selected international markets) for adults, especially those at elevated risk (e.g., aged 50+), and requires provider prescription.
- In Colorado, it is offered through numerous functional and integrative practices, including providers who refer to us, i.e. Cora Matteson, PA-C at The Live Well Center in Littleton at (720) 815-9303.
- Galleri is intended as an adjunct—not a substitute—for standard cancer screening modalities.
RGCC
- RGCC testing is accessible through clinics affiliated with its network and select integrative/alternative medicine clinics due to lack of regulatory clearance.
- In Colorado, RGCC is offered through numerous functional and integrative practices. A client at The Thermogram Center, Paulette Coates, DNM at Essential Wellness and (720) 581-1804, prescribes RGCC as well.
- RGCC evaluations are offered to both diagnosed cancer patients (for monitoring/guidance) and, less frequently, as screening in asymptomatic persons. Mainstream medical providers generally do not endorse RGCC screening due to validity concerns.
Pricing / Cost
Galleri – Self-pay pricing typically ranges from approximately $799 to a list price of $949, inclusive of the blood draw when performed at an authorized lab Galleri. Insurance coverage is limited (not widely covered by most insurers; Medicare and Medicaid generally don’t cover).
RGCC – Costs vary according to the type of test requested. For example, the Onco-D-Clare screen is listed at roughly $869, RGCC, while extensive panels such as Onconomics Plus may reach $2,226 or higher. Listed prices generally do not include ancillary fees (blood draws, shipping, consultations, etc.), which differ by clinic and location. Most patients pay out-of-pocket due to non-standard status in the U.S.
Appropriate Candidates and Cautions
Galleri may be suitable for:
- Adults (particularly ≥50 years) at elevated cancer risk seeking comprehensive screening.
- Individuals willing to accept limitations (i.e., a negative result won’t guarantee no cancer; a positive requires follow-up).
- Those eligible for self-payment or with applicable employer-provided health spending accounts.
RGCC may be appropriate for:
- Patients with confirmed cancer diagnoses seeking supplementary data (e.g., circulating cells, therapy sensitivities), ideally in collaboration with an oncologist.
- Persons interested in integrative or alternative medicine, acknowledging the results may be more speculative than standard-of-care diagnostics.
- Individuals prepared for direct payment and cognizant of the limited scientific validation.
Important caution: For otherwise healthy individuals without symptoms, using RGCC (or similar unproven blood-test trees) as a standalone “screening” tool carries risk – potential false positives or negatives can lead to unnecessary anxiety, potentially harmful follow-ups, or false reassurance.
Perspectives from the Medical/Clinical Community
Regarding Galleri, the prevailing view among clinicians is that it should augment, but not replace, conventional cancer screening protocols. Its principal utility may lie in detecting malignancies for which no standard screening exists.
Concerning RGCC, many mainstream oncologists and regulatory-review sources raise caution: the lack of robust, peer-reviewed evidence and regulatory approval make it unsuitable as a standard screening tool for general populations. Some components of RGCC (e.g., therapy-sensitivity assays, “alternative treatments,” or supportive therapies) are especially controversial and considered experimental.
Summary and Considerations
After delineating some of the strengths and limitations of the Galleri and RGCC blood tests to assist individuals in evaluating the appropriateness of each test blood-based screening, either should serve as a supplement—not a replacement—to established preventive care strategies.
For individuals seeking an extensively studied, advanced screening option, Galleri presents notable advantages—including the breadth of cancers covered, high specificity, and organ prediction capabilities.
Those contemplating RGCC should exercise substantial caution. While it may generate additional insights for patients already diagnosed with cancer under specialist supervision, its appropriateness for population-level cancer screening is unsupported by robust evidence.
In conclusion, new or lesser-validated assays warrant careful consideration, and decisions should be made in consultation with qualified healthcare professionals.