AINEWS
The $11.57 billion gatekeeper: the tests that decide which cancer drug you get
A companion diagnostic is the genetic test a patient must pass before insurers and oncologists will prescribe a targeted cancer drug.
A companion diagnostic is the genetic test a patient must pass before insurers and oncologists will prescribe a targeted cancer drug.
The tumor board at a regional cancer center runs on Tuesdays. By 9 a.m. the pathologists, oncologists, and a pharmacist have already pulled up the molecular profile for the patient in chair six, a 64-year-old with non-small cell lung cancer whose biopsy came back from a Foundation Medicine liquid biopsy three days earlier. The board's job is to pick the drug. The patient's job, before the drug, is to pass a test.
That test is what the trade calls a companion diagnostic: a laboratory assay whose result determines whether a specific drug is prescribed, denied, or never tried. Mordor Intelligence, citing the FDA companion diagnostics list, counts more than 160 such biomarker-drug pairings linked to approved tests. The commercial market for those tests is now large enough that two competing research firms have made it a headline category. MarketsandMarkets projects the global companion diagnostics market at $6.31 billion in 2026, climbing to $11.57 billion by 2031 at a 12.9% compound annual growth rate. Mordor Intelligence, sizing the same market independently, lands at $9.76 billion in 2026 and a $17.35 billion 2031 figure at 12.18% CAGR. The two firms agree on growth velocity and disagree on absolute size by roughly 50 percent.
That gap is the story behind the press release. Companion diagnostics are not a commodity; they are the gating infrastructure through which precision oncology either reaches a patient or does not. The press release version of this story is "market is big and growing." The actual market is a stack of regulated assays, payer rules, lab workflows, and a small number of dominant test makers whose products sit at the meeting point of FDA approval, drug labeling, and insurance reimbursement.
Pharmaceutical and biotechnology companies are the largest customer segment, holding about 44.6% of 2025 demand according to Mordor Intelligence, with MarketsandMarkets describing pharma as the dominant 2025 buyer. That is structurally important: companion diagnostics are mostly paid for, ordered, and designed around the launch economics of targeted drugs, not around the patient directly. A test exists because a drug label requires it, and a drug label is written by the company that wants to sell the drug.
Assays, kits, and reagents made up 65.75% (Mordor) to 67.3% (MarketsandMarkets) of 2025 product revenue, which is the unsexy bulk of the market: physical chemistry, not software. The fastest-growing slice of the same product pie is interpretive software, projected at about 15.12% CAGR through 2031 per Mordor Intelligence, driven by AI variant interpretation in next-generation sequencing labs. The fastest-growing sample type is liquid biopsy, at roughly 18.22% CAGR through 2031, while tissue biopsy still accounted for about 77.95% of 2025 volume.
North America held between 39.95% (Mordor) and 44.7% (MarketsandMarkets) of 2025 share. Asia-Pacific is the fastest-growing region at about 12.45% CAGR through 2031, with Mordor Intelligence attributing the growth to expanding clinical trial activity and rising oncology investment. Cancer is the dominant indication, with lung cancer at 22.10% of 2025 indication share and melanoma projected as the fastest-growing cancer indication at 13.22% CAGR.
The current growth story has a specific trigger. Foundation Medicine's FoundationOne Liquid CDx, a comprehensive liquid biopsy panel used to match patients to targeted therapies, received multiple FDA approvals in 2024 according to Mordor Intelligence, a regulatory tempo the firm flags as a marker of momentum for the broader liquid-biopsy companion diagnostic category. That is the kind of co-approval that turns a press release into a budget line item for a hospital system.
What neither vendor report quantifies, and what the headline growth rate does not capture, is who actually gets tested. A companion diagnostic that exists on paper, is approved by the FDA, and is named in a drug label still requires a clinician to order it, a lab to run it, and a payer to pay for it. The Mordor Intelligence report cites a payer reality in which reimbursement is increasingly tied to molecular confirmation of the biomarker the drug targets, which is a polite way of saying insurers are starting to write the gatekeeping rules that the FDA used to write.
The next thing to watch is whether the 12% growth rate the two research firms agree on translates into the 12% growth rate of patients actually receiving matched therapy, or whether the gap between the two numbers becomes the more interesting one. The market for the tests is growing fast. The market for getting the test is a separate, smaller, and less documented thing.