Cancer Research: A new urine test developed by Stanford Medicine researchers can make bladder cancer diagnosis less invasive and help doctors choose more effective treatments, according to a study. The test developed by Stanford researchers and the VA Palo Alto Health Care System has shown potential to diagnose bladder cancer more accurately than current standard tests, while also helping doctors predict which patients are likely to benefit from immunotherapy or chemotherapy. The findings were published in 'Nature Medicine' on October 2, 2026.
According to the research, the test, called uRARE-seq, measures RNA fragments shed by tumour cells into urine. Unlike most liquid biopsies, which look for cancer-related DNA mutations, RNA analysis reveals which genes cancer cells are actively using, offering clues not only to the presence of cancer but also to its behaviour.
"Measuring tumour DNA in urine can tell us whether a cancer is present," said senior author Dr Maximilian Diehn, professor of radiation oncology at Stanford. "Analysing RNA can tell us not only whether a cancer is present-but also what it's doing," he added.
In a study of 683 urine samples from patients and healthy volunteers, uRARE-seq correctly identified 95 per cent of people with localised bladder cancer and correctly gave a negative result to 90 per cent of those without the disease. The researchers said it performed better than standard urine cytology and a DNA-based urine test.
The test also distinguished low-grade from high-grade bladder cancer and detected residual disease after surgery and after BCG immunotherapy, a treatment in which a weakened tuberculosis vaccine bacterium is placed directly into the bladder to stimulate an immune attack on remaining cancer cells.
The study found that patients who later responded to BCG had pre-treatment urine RNA signals enriched for genes linked to T-cell and immune-signalling activity. Patients who did not respond showed signs of rapidly dividing tumour cells.
Using these patterns, researchers developed a biomarker that predicted with high accuracy whether a tumour was more likely to respond to immunotherapy or chemotherapy. This could eventually help clinicians reserve BCG for patients most likely to benefit.
The study noted that bladder cancer is diagnosed in about 85,000 people in the United States each year and is prone to recurrence. Current diagnosis and surveillance rely heavily on cystoscopy, in which an endoscope is inserted into the bladder; the researchers said the procedure can miss up to 30 per cent of cancers, while high-risk patients may need surveillance every three months.
A validated urine-based test can reduce the burden of repeated invasive procedures, enable earlier detection of recurrence, and support more personalised treatment decisions. "There are currently no biomarkers at all that are recommended or approved for surveillance," said senior author Dr Joseph Liao, chair of urology at Stanford. "If we can guide those choices, we have the potential to help both patients and clinicians," he stated.
The researchers plan to validate uRARE-seq in larger, prospective, multi-centre trials before it can be considered for standard diagnosis, surveillance or treatment selection.
The study included researchers from Resero Bio, a Stanford spinout formed to commercialise the technology, and the VA Palo Alto Health Care System. Several authors have ownership interests in Resero Bio or patents related to urine cell-free RNA analysis, according to the university's disclosure.
