The distinction between reading DNA and reading RNA is central to why this test works so well. DNA mutations reveal that a cancer exists, but they say little about what the cancer is actually doing inside the body. RNA, by contrast, reflects which genes a cell is actively using at a given moment, offering a dynamic snapshot of tumor behavior. Maximilian Diehn, MD, PhD, the Jack, Lulu, and Sam Willson Professor and a professor of radiation oncology at Stanford, explained the difference in practical terms: measuring tumor DNA in urine can tell clinicians whether a cancer is present, he said, but analyzing RNA can tell them not only whether a cancer is present but also what it is doing. That added layer of information is what allows the test to move beyond diagnosis and into the realm of treatment prediction.

The clinical need for better tools is substantial. Roughly 85,000 people in the United States are diagnosed with bladder cancer each year, and the disease is notoriously prone to recurrence and expensive to monitor. Diagnosis and surveillance currently depend on cystoscopy, a procedure in which an endoscope is threaded into the bladder to visually inspect for suspicious tissue. Cystoscopy can miss up to 30 percent of cancer cases, and patients with a history of non-muscle-invasive bladder cancer may need to undergo the procedure as often as every three months for the rest of their lives. The physical burden, the anxiety, and the cumulative cost of this surveillance regimen make a reliable noninvasive alternative one of the most sought-after goals in urologic oncology.

Diehn and Ash Alizadeh, MD, PhD, the Moghadam Family Professor, have collaborated on liquid biopsy technology for more than a decade. In 2014, the pair developed CAPP-Seq, short for cancer personalized profiling by deep sequencing, a method capable of detecting trace amounts of tumor DNA in the blood of lung cancer patients. The technique was later shown to classify lymphoma subtypes and flag emerging drug resistance. The researchers wondered whether a similar approach applied to urine could enhance the diagnosis, monitoring, and treatment of bladder cancer, but the bladder presented unique challenges that made a straightforward adaptation impossible.

The central problem is something researchers call the field effect. Normal bladder lining cells often accumulate their own mutations that overlap with those found in a patient’s actual tumor, a consequence of the same environmental exposures, such as smoking, that drive bladder cancer in the first place. A DNA-based test can mistake these bystander mutations for cancer, and correcting for the error typically requires first sequencing a patient’s tumor and normal tissue to learn which mutations to track and which to disregard. RNA-based testing sidesteps this obstacle entirely. Because RNA messages reflect overall gene activity rather than individual mutations, the test does not require matched tumor samples. Alizadeh noted that for DNA-based, tumor-informed approaches, clinicians need to know exactly what a tumor’s mutations look like to track disease, whereas RNA offers a biological signature of disease rather than an exact likeness, and urine provides a noninvasive way to detect and track it.

Designing a urine-based RNA test was nonetheless technically demanding, because RNA molecules in urine are fragmented and relatively rare. The research team, led by graduate student Kevin J. Liu, adapted a genetic sequencing method originally designed for RNA in blood plasma and designed a custom gene panel to identify RNA messages that are rare in healthy urine but abundant when a patient has a genitourinary tumor. The resulting assay, named uRARE-seq, which stands for urine random priming and affinity capture of cell-free RNA fragments for enrichment analysis by sequencing, was applied to samples from patients with bladder, kidney, and prostate cancer. It closely tracked the biology of the tumors and could even distinguish low-grade from high-grade bladder cancer, an important distinction that guides how aggressively a tumor must be treated.

The performance figures are striking. In a study of 683 urine samples from patients and healthy volunteers, uRARE-seq correctly identified 95 percent of people with localized bladder cancer and correctly cleared 90 percent of those who did not have the disease. That sensitivity and specificity outperformed both standard urine cytology, in which urine is examined under a microscope to identify cancerous cells, and an existing DNA-based urine test. The test also proved capable of identifying residual disease left behind after surgery and after BCG immunotherapy, giving clinicians a way to assess treatment response without repeated invasive procedures.

Perhaps the most consequential finding concerns treatment prediction. The researchers discovered that patients who subsequently responded to BCG therapy had pre-treatment urine RNA messages rich in genes involved in T-cell and immune-signaling activity, while those who failed to respond showed molecular signs of rapidly dividing tumor cells. Leveraging this insight, the team developed a biomarker that predicted with high accuracy whether a patient’s tumor was more likely to respond to immunotherapy or to chemotherapy, which is currently used as a second-line treatment when BCG fails or is unavailable. Joseph Liao, MD, the Kathryn Simmons Stamey Professor and chair of the department of urology, shares senior authorship of the study with Diehn and Alizadeh, and emphasized the stakes involved in getting these treatment decisions right.

The supply dynamics of BCG make this predictive capability especially valuable. BCG, a weakened strain of the bacterium used in tuberculosis vaccines, is instilled directly into the bladder through a catheter once a week for six weeks, with maintenance courses that may continue for up to three years. It works by stimulating the patient’s immune system to destroy lingering cancer cells, but it does not work for everyone, since some tumors simply lack the underlying immune activity needed to mount an effective response. Critically, BCG is manufactured by a single global supplier, and shortages are common, forcing urologists to ration doses among patients. A validated version of the test could allow doctors to reserve BCG for those most likely to benefit while moving other patients to chemotherapy sooner, sparing them months of ineffective therapy.

The researchers plan to validate uRARE-seq in larger, prospective trials at multiple centers, with the aim of bringing personalized treatment to bladder cancer patients. Liao pointed out that there are currently no biomarkers at all recommended or approved for surveillance in bladder cancer, and that the existing treatments are incredibly taxing, both physically and financially; guiding those choices, he said, has the potential to help both patients and clinicians. Researchers from Resero Bio, a Stanford spinout based in San Carlos formed to commercialize the technology, and the VA Palo Alto Health Care System contributed to the study. The work was funded by the National Institutes of Health, the Stanford ACED Canary Fellowship, the Tobacco-Related Disease Research Program, and the Virginia and D.K. Ludwig Fund for Cancer Research, among other sources, and several authors hold ownership interests in Resero Bio or related patents and consulting roles.

Subject of Research: Urine cell-free RNA sequencing for bladder cancer detection and treatment response prediction

Article Title: Urine test may improve bladder cancer diagnosis and guide treatment decisions

Article References: Urine test may improve bladder cancer diagnosis and guide treatment decisions. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: bladder cancer, liquid biopsy, urine test, cell-free RNA, uRARE-seq, BCG immunotherapy, chemotherapy, biomarker, cystoscopy, Nature Medicine, Stanford Medicine, precision oncology

Renal cell carcinoma ranks as the seventh most common malignant tumor in men and the tenth most common in women worldwide. Roughly one in four to one in three patients already harbor distant metastases when they are first diagnosed, with the disease seeding most frequently into regional lymph nodes, lungs, bones, and liver. Yet the bladder is an extraordinarily uncommon destination. Fewer than seventy cases of bladder metastasis from renal cell carcinoma have ever been reported in the medical literature, and virtually none have described this pattern emerging after a patient had already undergone radical nephrectomy, metastasectomy, and multiple lines of targeted therapy. That is precisely what makes this new case, published in Clinical Case Reports by clinicians at the First Affiliated Hospital of Zhejiang University School of Medicine, so noteworthy.

The technical details of the initial diagnosis illustrate how modern imaging dissects a renal mass. Contrast-enhanced computed tomography showed the tumor lighting up intensely during the arterial phase, a signature of the rich, disordered blood supply that characterizes clear cell carcinoma, while uneven enhancement pointed to localized ischemic necrosis deep within the lesion. These findings ruled out the principal differential diagnoses, including renal tuberculosis, kidney stones, renal cysts, and hamartomas, and staged the disease as T4N0M1, meaning a locally advanced primary tumor with distant metastatic involvement but no lymph node spread. Surgeons proceeded with a laparoscopic radical left nephrectomy, and pathology under the microscope confirmed clear cell renal cell carcinoma.

Because the disease was already metastatic at diagnosis, the oncology team initiated adjuvant systemic therapy with sunitinib, a tyrosine kinase inhibitor delivered at fifty milligrams daily. Sunitinib has historically been a cornerstone of first-line treatment, with landmark trials demonstrating significantly prolonged overall survival compared with interferon alpha. In this patient, however, the drug failed. Within three months, follow-up CT scans showed clear progression of the metastasis in the right adrenal gland. Surgeons removed the gland, pathology again confirming infiltration by clear cell carcinoma, and the team switched to a second tyrosine kinase inhibitor, axitinib at five milligrams twice daily, with imaging every three months. The message was already becoming unmistakable: this tumor was proving refractory to the standard pharmacological arsenal.

Ten months after the original surgery, the patient developed pain in her right thumb. Hand CT imaging revealed osteolytic bone destruction, a hole eaten into the base of the first metacarpal by metastatic cells, with associated soft tissue involvement. Surgeons resected the metastatic bone tumor, reconstructed the defect with a bone graft, and fixed it internally. Pathology confirmed clear cell renal cell carcinoma metastasis. One week later, a whole-body F-18 FDG PET/CT scan was performed, and the results expanded the map of the disease dramatically: the tracer lit up metastatic deposits in the skull, and, remarkably, in the bladder.

Cystoscopy, the direct visual inspection of the bladder interior, revealed two red neoplastic lesions on the bladder wall. Transurethral resection removed the tissue, and histopathological examination confirmed the stunning diagnosis: metastatic clear cell renal cell carcinoma growing inside the bladder, entirely asymptomatic. This last point carries real clinical weight. According to prior literature, roughly seventy percent of patients with bladder metastasis from renal cell carcinoma present with hematuria, visible blood in the urine. This patient had none. Her bladder metastasis was found purely incidentally on PET imaging, a discovery that would likely have been delayed, perhaps indefinitely, in a less thoroughly monitored patient.

Facing relentless progression, the clinicians escalated to combination therapy, pairing axitinib with toripalimab, an immune checkpoint inhibitor, at 240 milligrams. The rationale rested on recent phase III evidence from the RENOTORCH trial, which demonstrated that the combination of toripalimab and axitinib delivered superior clinical benefit compared with sunitinib monotherapy as first-line treatment for advanced renal cell carcinoma. The combination appeared to achieve local control where it mattered most in this case: after transurethral resection of the bladder tumor, follow-up cystoscopic examinations showed no evidence of bladder tumor recurrence, even after a full year of continuous combination therapy. Yet the systemic disease refused to stand still. Three months before the report was finalized, routine abdominal CT revealed new metastatic lesions in the right ninth rib and in the bilateral iliac bones of the pelvis, signaling that distant skeletal spread was continuing despite the intensified regimen.

The trajectory of this case underscores a sobering paradox in contemporary kidney cancer treatment. Targeted therapy and immunotherapy have genuinely transformed outcomes in advanced renal cell carcinoma, extending survival in large prospective clinical trials and converting what was once an almost uniformly fatal diagnosis into a chronic disease for many patients. Prolonged survival, however, creates a longer window in which the biology of the tumor can express itself in unusual ways, and clinicians are increasingly reporting metastases to rare sites such as the esophagus, the eyeball, and now the bladder. Previous case reports of bladder metastasis typically described patients with localized renal tumors who developed isolated bladder recurrence several years after partial or radical nephrectomy, without disease elsewhere, or involved non-classical histological subtypes. No previous report, as far as the authors know, had documented bladder metastasis in advanced renal cell carcinoma developing after first-line targeted therapy in a patient with widespread systemic disease.

Over the course of her care, this patient underwent five salvage tumor resections, including the nephrectomy, adrenalectomy, metacarpal resection, cranial metastasis resection, and transurethral bladder tumor resection, alongside continuously evolving systemic therapy. The authors emphasize that resecting bladder metastases may reduce local recurrence but cannot suppress distant spread, and that there is currently no standardized clinical guideline for managing bladder metastasis of renal cell carcinoma at all. For patients like this one, who remain refractory to first-line and second-line regimens and continue to accumulate metastases, the authors argue that genomic profiling to identify novel therapeutic targets may offer the next realistic avenue of clinical benefit. The patient remains under active follow-up, generally stable in condition even as her bone metastases progress, and her treatment regimen is expected to require further adjustment.

The broader lesson for clinicians and researchers alike is vigilance. Bladder metastasis of renal cell carcinoma is rare enough to escape suspicion, and its frequent association with hematuria means an asymptomatic presentation, as in this case, could easily evade detection without systematic PET/CT surveillance and cystoscopic confirmation. As targeted agents and immune checkpoint inhibitors continue to extend the lives of patients with metastatic kidney cancer, the population of long-term survivors will grow, and with it the likelihood that oncologists will encounter metastatic patterns that current guidelines never anticipated. This single patient’s two-year journey, from an incidental ultrasound finding to a bladder seeded with kidney cancer that never once bled, is a vivid reminder that in advanced clear cell renal cell carcinoma, the map of metastasis is still being drawn, and every unusual case redraws it a little further.

Subject of Research: A rare case of asymptomatic bladder metastasis from advanced clear cell renal cell carcinoma following radical nephrectomy, metastasectomy, and targeted and immunotherapy.

Article Title: Metastatic Clear Renal Cell Carcinoma in Bladder Following Radical Nephrectomy, Metastasectomy, and Targeted Therapy: A Rare Case Report

Article References: Zheng, X., Jiang, P., & Zhou, J. (2026). Metastatic Clear Renal Cell Carcinoma in Bladder Following Radical Nephrectomy, Metastasectomy, and Targeted Therapy: A Rare Case Report. Clinical Case Reports, 14(9), Article e73557. https://doi.org/10.1002/ccr3.73557

Image Credits: AI Generated

DOI: 10.1002/ccr3.73557

Keywords: clear cell renal cell carcinoma, bladder metastasis, radical nephrectomy, sunitinib, axitinib, toripalimab, tyrosine kinase inhibitor, immunotherapy, bone metastasis, FDG PET/CT, cystoscopy, case report