Patients are often handed a menu of advanced tests — RGCC, DATAR, Tempus, Celcuity, Signatera, Astron Health — with little explanation of what separates them. They are not competing versions of the same thing. Each answers a different question, and the right one depends entirely on where you are in your treatment journey.
Before agreeing to any of them, ask one question: what decision will this result actually change? If there isn't a clear answer, the test isn't ready to be ordered yet.
The most common mistake I see is ordering a test because it came up in a support group or a search result, rather than because a specific decision depends on it.
None of the tests below find a first cancer. They all assume a diagnosis already exists. What they do is help answer one of three questions — and knowing which question you're actually asking makes the choice much simpler.
These try to answer what is most likely to work. Tempus sequences your tumor's DNA to find the mutations driving it, then looks for a targeted drug or clinical trial built for that specific break in the machinery. Celcuity's CELsignia takes a different approach — instead of reading the genetic code, it watches whether specific signaling pathways are actively firing inside live tumor cells. That distinction matters, because a mutation can be present on paper without actually driving the tumor's behavior.
RGCC and DATAR work from a blood draw, isolating circulating tumor cells and exposing them to a panel of agents in the laboratory to see which ones affect them. This can be genuinely useful for narrowing a long list of drug options, or for building confidence in a direction your team was already leaning toward. It's most often used when standard options have been exhausted and the question is how to rank what remains.
Signatera isn't picking a drug. It looks for fragments of tumor DNA circulating in your blood after treatment, with the goal of catching residual or returning disease earlier than a scan would show it. Timing is everything here: it comes into play after surgery or after finishing a course of treatment, when the question shifts from what should we treat with to is anything left, and how early can we know.
A newly diagnosed patient hasn't generated a baseline yet, so this test's role typically arrives later in the journey.
Astron isn't a lab and doesn't process a sample. It reviews the records you already have — pathology, genomics, imaging, history — and synthesizes them into an expert-level strategy review. Think of it as a second brain reading your chart rather than another vial going to a lab.
That synthesis step is one many patients never get, particularly outside major academic centers. It is generally most valuable layered on top of results from the other tests, not instead of them.
| Test | What it looks at | Sample | Mainly used for | Regulatory status |
|---|---|---|---|---|
| Tempus | Mutations in the tumor's DNA | Tumor tissue | Matching targeted drugs and trials | xT CDx carries FDA approval for one specific colorectal indication; other applications run as CLIA-validated lab tests |
| Celcuity (CELsignia) | Whether signaling pathways are actively firing in live cells | Fresh biopsy | Confirming a pathway is truly active before using a drug aimed at it | CLIA-validated laboratory-developed test |
| RGCC | How circulating tumor cells respond to a panel of agents in the lab | Blood draw | Narrowing or ranking drug options | CLIA-validated laboratory-developed test |
| DATAR | Similar, using an ex vivo culture of tumor cells | Blood draw / tissue | Narrowing or ranking drug options | CLIA-validated laboratory-developed test |
| Signatera | Fragments of tumor DNA circulating after treatment | Blood draw | Detecting residual or returning disease before imaging does | CDx carries FDA approval for one specific bladder cancer indication; other applications run as CLIA-validated lab tests |
| Astron Health | Your existing records, reviewed by experts | None | Second-opinion treatment strategy | Not a diagnostic test |
Regulatory status reflects our understanding at the time of publication and changes over time. Confirm current status and coverage for your own situation.
This is the part I most want patients to understand, because it's rarely explained.
A laboratory cytotoxicity assay is built around a single question: does this agent directly kill the cell in front of it? For a conventional chemotherapy drug whose mechanism is direct cell kill, that's a reasonable model of what the drug does.
These panels usually also report on natural agents — IV vitamin C, mistletoe, artesunate, curcumin and others. Here the model and the mechanism don't line up as neatly. Several of these agents are understood to work in the body largely by engaging the immune system and changing the environment around the tumor — not by poisoning cells on contact. A dish has neither an immune system nor a tumor microenvironment to recruit.
So a "resistant" reading for one of those agents may reflect the limits of what an in-dish test can capture, rather than evidence the agent doesn't work. This isn't a criticism of the laboratories — it's an inherent constraint of any test performed outside a living body.
Practical takeaway: the conventional-drug portion of these reports and the natural-agent portion carry different weight. Ask your clinician which mechanism the assay is modeling before ruling anything in or out on the strength of the report alone.
FDA approval attaches to a specific indication — a particular cancer type and a particular clinical decision — not to everything a testing company offers. A platform can hold an approval for one cancer type and be used as a validated laboratory test for every other. Both can be legitimate; they sit at different evidentiary bars. The useful question is: which indication does that approval actually cover, and is it mine?
Insurance coverage tracks the specific covered indication, not the brand name on the report. And the two don't move together the way people assume — "FDA-approved" doesn't automatically mean covered, and a laboratory-developed test isn't automatically uncovered; Medicare has covered several such applications for years. Ask about coverage for your diagnosis, in writing, before the draw.
A favorable marker or a strong sensitivity score shifts the odds in a direction. It does not guarantee a response. No test on this list can account for how your immune system, inflammatory state, and metabolic health will shape what a treatment actually does once it's inside you.
That's the reasoning behind how we work at Root Causes Oncology. These tools describe the tumor with real precision. They say very little about the terrain that tumor is living in — the inflammatory, metabolic, and immune conditions around it. Both drive outcomes, and only one of them shows up on the report. We use a terrain assessment to decide which tests are worth running in the first place, rather than running everything available and sorting it out afterward.
Don't order a test because you saw it online or heard about it from another patient. Order it because you and your oncologist have a specific decision it's meant to inform. Testing describes the tumor; terrain work addresses the environment it's growing in. A real strategy has to answer to both at once.
Disclaimer. This guide is general educational information, not medical advice, and does not establish a physician–patient relationship. It does not diagnose, treat, or recommend therapy for any individual, and no outcome is implied or promised. Test names are referenced descriptively for educational purposes; Root Causes Oncology has no financial relationship with the companies named and makes no representation as to the performance of their products. Regulatory and coverage information reflects our understanding as of July 2026 and may change. Always discuss testing and treatment decisions with your own licensed oncology team.