A new blood test called Latitude may help more people with colorectal cancer benefit from MRD (minimal residual disease) testing and more personalized treatment decisions. Latitude is a tissue‑free, methylation‑based ctDNA blood test that can detect microscopic colorectal cancer months before scans and help clarify who truly needs chemotherapy after surgery—even when tumor tissue is limited or unavailable.
In the GALAXY study, which included 195 patients and more than 1,300 blood samples, patients who were Latitude‑negative after surgery had much longer times without disease than those who were Latitude‑positive, with about a 10‑fold difference in risk of recurrence (hazard ratio ~10, p<0.001). Latitude showed about 58% sensitivity at a single MRD time point, which increased to around 81–84% when patients were followed over time, along with very high specificity: about 97% of individual blood samples from people without recurrence tested negative. On average, the test detected recurrence about 4.6 months before it became visible on scans.
The study also suggests Latitude could help clarify who truly benefits from adjuvant chemotherapy (ACT). Patients who tested Latitude‑negative after surgery appeared to gain little additional benefit from ACT, while Latitude‑positive patients did better if they received ACT than if they did not. In fact, all Latitude‑positive patients who skipped ACT later relapsed, indicating a positive predictive value of 100% in that group (26 of 26 patients), which underscores how strongly a positive result is linked to hidden residual cancer.
Importantly, for patients with high‑risk stage II or stage III colorectal cancer, those who were ctDNA‑positive seemed to benefit from receiving chemotherapy after surgery, while ctDNA‑negative patients did not show the same benefit. This suggests the test might one day help personalize decisions about who truly needs additional treatment and who may be able to avoid it.
What to ask your doctor about Latitude
Patients might consider bringing these questions to their next visit:
- “Am I a candidate for the Latitude tissue‑free MRD test based on my stage and treatment plan?”
- “How is Latitude different from tumor‑informed tests like Signatera, and why might one be better for my situation?”
- “When would my blood be drawn for Latitude, and how often would you repeat the test?”
- “How would a negative Latitude result affect decisions about chemotherapy, scans, and follow‑up?”
- “How would a positive Latitude result change my treatment plan—would you recommend chemotherapy, a clinical trial, or closer imaging?”
- “If my original tumor sample is small or hard to access, does Latitude give us an alternative way to monitor for recurrence?”
- “Will my insurance cover Latitude, and is there financial assistance if it is not fully covered?”
More Reading
Frequently Asked Questions about ctDNA and Colon Cancer
Reference
Nakamura Y, Reiter JG, Natarajan P, et al. Validation of a methylation-based, tissue-free MRD assay in colorectal cancer patients from the GALAXY study. NPJ Precis Oncol. 2026 Jan 19.
