The Cocktail Report (sound really smart around your friends):
MRD (minimal residual disease) testing uses circulating tumor DNA (ctDNA), tiny fragments of cancer cell DNA floating in the bloodstream after surgery, to detect whether any cancer cells remain before they grow large enough to appear on a scan.
Signatera, made by Austin-based Natera, is tumor-informed: it sequences the removed tumor's unique genetic signature and then builds a personalized blood test to hunt specifically for those mutations in future blood draws.
The phase 3 IMvigor011 trial, published in the New England Journal of Medicine, showed that bladder cancer patients who tested Signatera-positive and received immunotherapy had a median overall survival of 32.8 months versus 21.1 months for those who did not.
Patients who remained Signatera-negative after surgery (meaning no detectable residual disease) had overall survival rates of 100% at 12 months and 98% at 18 months without any additional treatment.
MRD testing currently reaches only about 6% of the estimated $20 billion domestic eligible market, meaning most cancer survivors have never heard of it.
Here is a fact that should matter to anyone who has had cancer, or loves someone who has: by the time a tumor shows up on a scan, it may already be too late to treat it most effectively. A blood test now exists that can detect cancer returning months before imaging can see it.
The test is called Signatera, and it works differently from other cancer blood tests. When a tumor is removed, Natera sequences its DNA to identify a unique genetic fingerprint, then builds a personalized blood test that searches for those exact mutations in every future blood draw.
This approach is called MRD (minimal residual disease) testing: detecting cancer at the molecular level before it becomes visible on any scan.
"By the time a tumor shows up on imaging, it's often too late," said Neel Talwar, an oncologist at City of Hope. "Chemotherapy is much more effective at eradicating minimal disease than it is at eradicating macroscopic disease that you can already see on imaging.
The clinical evidence is now substantial. In the IMvigor011 phase 3 trial, published in the New England Journal of Medicine, bladder cancer patients who tested Signatera-positive and received immunotherapy had a median overall survival of 32.8 months, compared to 21.1 months for the placebo group.
That is a 41% improvement in overall survival, driven entirely by acting on a blood test result.
Equally important: patients who consistently tested Signatera-negative after surgery did exceptionally well without any additional treatment. Their overall survival was 100% at 12 months and 98% at 18 months, suggesting the test can also prevent unnecessary chemotherapy in patients who do not need it.
That two-sided value (treating those who need it, sparing those who do not) is what distinguishes MRD testing from most oncology tools, which lean toward overtreating rather than risk missing recurrence.
Natera has submitted an FDA application for Signatera as a companion diagnostic in bladder cancer, with approvals expected to expand to colorectal cancer and other tumor types as additional trial data matures. Medicare already covers the test; commercial insurers currently cover it only about 25% of the time, which is the main barrier limiting access.
The lead time advantage is the key number to hold onto. In colorectal cancer studies, Signatera detected recurrence a median of 4.6 months before it appeared on imaging.
That window is when treatment is most likely to work.
Why Should You Care?
If you or someone close to you has been treated for any solid tumor cancer, this test is worth asking your oncologist about by name. Coverage and availability vary, but the clinical evidence is strong and growing across multiple cancer types.
More broadly, this is what precision medicine looks like in practice: not a one-size-fits-all scan, but a test built from your specific cancer's DNA, watching for the exact mutations that could signal its return.
Sources:
1. IMvigor011 trial results — New England Journal of Medicine (presented at ESMO 2025): https://www.natera.com/company/news/successful-imvigor011-trial-achieves-41-improvement-in-overall-survival-for-bladder-cancer-patients/
2. Natera Latitude colorectal MRD validation — npj Precision Oncology (Jan 2026): https://investor.natera.com/news/news-details/2026/Natera-Publishes-Clinical-Validation-of-Latitude-Tissue-Free-MRD-Test-in-Colorectal-Cancer/default.aspx
3. Wainer D. "The Cancer Test That Wall Street Is Betting On." The Wall Street Journal, May 14, 2026.
