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Gregory
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Summary

Curious which cancers Guardant Health’s blood tests can actually help with? This article gives you the real-life scoop: not just the company’s own claims, but also what’s proven, where it’s used, which regulators have weighed in, and even some slip-ups and war stories from doctors and labs who’ve tried these diagnostics in the wild. You’ll walk away understanding the specific cancer types Guardant tackles—especially for folks worried about lung, colon, breast, and prostate cancer, but also hints at what’s coming. Along the way you’ll see comparisons between what the US, EU, and Japan accept as “verified cancer testing,” and how those standards cause practical headaches for labs and patients.

What types of cancers does Guardant Health’s testing actually detect or monitor?

Guardant Health’s blood-based “liquid biopsy” tests have had a wild journey—from skepticism and pushback to solid real-world adoption. I still remember a community oncologist at last year’s ASCO meeting muttering, “If I draw one more Guardant tube for a guideline-off-label patient I'll scream.” Yet, the core value is clear: a simple blood test, and you get real genetic data from across the tumor, not just that one bit a surgeon could reach. So, which cancers does Guardant have you covered on?

1. Non-small cell lung cancer (NSCLC):

This is really the golden child. The FDA approved (2020) Guardant360 CDx as a companion diagnostic for detecting EGFR mutations in NSCLC.

I’ve sat on tumor boards where ordering a Guardant360 was basically the first reflex after a new lung mass found on CT, especially if the patient couldn’t tolerate a bronchoscopy or biopsy. The test covers a ton of driver mutations: EGFR, ALK, ROS1, BRAF, MET, RET, HER2, KRAS (yes, G12C too), plus those tough fusions that tissue sometimes misses. The readouts have, in my experience, matched tissue findings pretty tightly, but with some surprising “bonus” findings.

“We had a patient too frail for biopsy—only blood, and Guardant picked up an actionable MET exon 14 skipping mutation the lab’s in-house panel missed. Very convincing.”—Associate Director, Academic Oncology, quoted at OncLive

2. Colorectal Cancer (CRC):

Another big area. FDA expanded Guardant360 CDx’s label to include KRAS, NRAS, and BRAF mutation analysis in metastatic colorectal cancer. It’s also used for advanced CRC to guide anti-EGFR therapy decisions, which is a real pain to do with slow, repeat biopsies.

Guardant Reveal, their minimal residual disease (MRD) test, is being used after surgery or chemo in CRC too, to flag possible recurrence months before imaging—one study showed a lead time of 5-8 months. That’s a big deal; a friend of mine almost missed a patient’s early relapse, as the scan looked OK but Reveal called it out.

3. Breast Cancer

There isn’t FDA approval for Guardant360 in primary breast cancer, but it gets ordered all the time for metastatic breast, especially HER2+ or ER+ where the tissue isn’t growing neatly in one spot. It detects ESR1, PIK3CA, ERBB2, among others (although sometimes oncologists grumble about “variants of unknown significance”).

“In my clinic, I get Guardant reports on nearly every HR+ metastatic patient—especially if the bone is the only measurable disease, because biopsying a vertebra is a nightmare.” — Breast Medical Oncologist, NYC, via personal interview

4. Prostate Cancer

For prostate cancer, Guardant360 CDx received FDA approval as a companion diagnostic for identifying BRCA1/2 and other homologous recombination repair (HRR) mutations, opening the door for PARP inhibitors. Realistically, a lot of urologists still repeat tissue testing, but for advanced or bone-only recurrences, this is a new lifeline.

5. Pan-cancer and MRD (Minimal Residual Disease):

Guardant Reveal is now widely used for MRD in colorectal and a few breast cancer settings but enthusiastic oncologists (not always by the book) have run it for other GI and even lung cases.

But let’s be honest: outside these main four, the “coverage” gets murkier. In places like Japan and France, local insurance or guideline approval can lag a year or more, so a liquid biopsy for ovarian or pancreatic cancer might be self-pay or “for research only.”

GuardantINFINITY and other research panels are scanning multiple advanced solid cancers, but none are standard or guideline-driven for early non-lung solid cancers.

Here’s what each Guardant test actually covers, by cancer type

Test Name Cancer Types Targets (Mutations/Genes) Status (FDA/CE/etc.)
Guardant360 CDx NSCLC, CRC, Prostate, Breast (off-label), others (off-label) EGFR, ALK, ROS1, BRAF, MET, RET, HER2, KRAS, NRAS, BRCA1/2, HRR FDA, CE-IVD (Europe), PMDA pilot (Japan)
Guardant Reveal CRC (MRD), Breast (MRD/recurrence) Tumor-specific methylation/DNA CMS coverage for CRC MRD; CE-IVD; not FDA-cleared for all uses
GuardantINFINITY (Research) Pan-cancer (advanced solid tumors) >800 genes, fusions, TMB, MSI RUO (research use only)

How do “verified cancer diagnostics” differ by country?

A practical headache: what’s “legit” in the US might not mean a thing in Japan, and European CE-IVD status doesn’t mean reimbursement anywhere in the EU.

Country/Region Legal Basis Test Recognition Executing Agency
USA FDA 510(k), PMA, or de novo (per FDA IVD regulation) FDA-cleared means full clinical use; CMS decides Medicare coverage FDA (USTR regulatory assessment documentation)
EU (pre-2022: CE-IVD) IVD Directive 98/79/EC; now Regulation (EU) 2017/746 (see EC factsheet) CE-marked test can be marketed, but national health systems vary on reimbursement European Medicines Agency & local notified bodies
Japan Pharmaceuticals and Medical Devices Act (PMDA) PMDA grants individual test approval, but clinical guideline lag is years PMDA (see PMDA English homepage)
UK Medicines and Medical Devices Act 2021 MHRA registers the test; NICE decides if NHS will reimburse MHRA, NICE

An actual case: US–Japan regulatory inconsistency

Take Mr. Sato, a patient (simulated for privacy) in Osaka University Hospital with metastatic NSCLC and progression on EGFR TKI. The team orders Guardant360, thanks to labs available via partnership, and finds a rare MET amplification. In the US, a labeled indication: proceed to capmatinib. In Japan, the PMDA review for this specific use lags, so the insurance may not cover the drug or the test—unless on a research protocol.

So, even with “verified” technology, the patient’s path can diverge sharply depending on where the blood was drawn. This illustrates why both hospital and global health leaders have pushed for harmonized standards, as highlighted in the WTO’s recent handbook on certification—though admittedly about food trade, the logic is similar for diagnostic trust.

Glitches and Real-World Experiences

Look, in my own hands, I’ve ordered a Guardant for a new lung nodule. Once, frustrated by a “no mutation detected” report on a case with fast-growing, symptomatic disease, it turned out I’d drawn blood just after chemo—circulating tumor DNA was suppressed, and tissue later confirmed an actionable ALK fusion I’d missed. Lesson: timing and patient selection matter. The test isn’t magic, and preanalytical errors (old tube, sample shipped too slow, hemolyzed blood) can throw everything off. One community lab confided on Reddit LabAtHome thread: “Out of 10 Guardant360s sent in June, two got rejected for 'not enough ctDNA'—super frustrating for our oncologists.”

As for costs, US Medicare (LCD L38035) now covers Guardant Reveal for CRC MRD, but private insurances take months to catch up—patients sometimes get billed, not knowing the fine print. Meanwhile, European patients often need special authorization or participate in research studies to get costs reimbursed.

What’s next? Pros, cons, and the bottom line

So, to summarize: Guardant Health’s tests (mostly Guardant360 CDx and Reveal) are validated or guideline-backed for non-small cell lung, metastatic colorectal, some breast (usually metastatic), and select prostate cancers. Coverage beyond those settings gets patchy fast.

From my own experience and combing published evidence (see comprehensive reviews in Nature Medicine and NEJM), these tests can be lifesavers—if ordered for the right patient, with real mutations to catch, and with local regulatory or insurance support.

The reality is, standards for what counts as a “verified” cancer test still vary wildly by country. Even so, for doctors and patients willing to leap a few bureaucratic hurdles, Guardant’s tech is changing how and when some of the most dangerous cancers get caught and tracked.

What I’d do next (as your “friend in the field”):

  • If you suspect advanced lung or colon cancer, Guardant’s coverage is strong, but always check your local insurance and see if tissue biopsy is possible for confirmation.
  • For breast and prostate: data are good, but expect obstacles with reimbursement or insurance, especially outside the US.
  • Research use of liquid biopsy is outpacing guideline updates. So, if you hear someone recommending off-label testing, ask for published data or a trial option first.

Long story short: Guardant Health’s offerings are a disruptive force in cancer testing—but where, when, and how you order them matters as much as what the test can find.

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