A new study from Stanford Medicine suggests that color vision deficiency—commonly known as colorblindness—may unintentionally delay the detection of bladder cancer. Researchers found that patients with both bladder cancer and colorblindness experienced a 52% higher long-term mortality risk compared with patients who have normal color vision.
The reason may lie in a simple but critical diagnostic signal: blood in the urine, the most common early symptom of bladder cancer.
For clinicians, diagnostic researchers, and healthcare laboratories, these findings highlight how sensory differences can influence disease detection, diagnostic timing, and ultimately patient outcomes.
Why Blood in Urine Matters
In many cases, hematuria (blood in the urine) is the earliest and most visible warning sign of bladder cancer. Detecting this symptom often prompts patients to seek medical evaluation, leading to earlier diagnosis and treatment.
However, individuals with color vision deficiency—particularly red-green colorblindness—may have difficulty identifying subtle changes in urine color. As a result, the presence of blood may go unnoticed for longer periods, delaying medical consultation and diagnostic testing.
Because bladder cancer survival rates are strongly linked to the stage at diagnosis, even small delays can significantly affect long-term outcomes.
Analyzing Millions of Health Records
To investigate the potential link between colorblindness and cancer outcomes, researchers analyzed large-scale electronic health record datasets using the TriNetX research platform. This global system aggregates real-time clinical data from hundreds of institutions and includes hundreds of millions of de-identified patient records.
From approximately 100 million U.S. patient records, investigators identified:
-
135 patients diagnosed with both color vision deficiency and bladder cancer
-
187 patients diagnosed with color vision deficiency and colorectal cancer
Each group was compared with matched control patients who had the same cancers but normal color vision.
The results revealed a striking difference in survival outcomes for bladder cancer patients.
A 52% Higher Long-Term Mortality Risk
Among bladder cancer patients, those with colorblindness showed a 52% higher mortality risk over a 20-year period compared with individuals who had normal color vision.
The study suggests that the difference likely arises from delayed recognition of hematuria. When the disease is detected later—after it has progressed or become invasive—treatment becomes more complex and survival rates decline.
As senior author Dr. Ehsan Rahimy, adjunct clinical associate professor of ophthalmology at Stanford, explained:
“I'm hopeful that this study raises some awareness… for patients with colorblindness and the clinicians who care for them.”
The findings highlight how seemingly unrelated biological factors—such as visual perception—can influence clinical outcomes.
Why Colorectal Cancer Showed Different Results
Interestingly, the same mortality pattern was not observed in colorectal cancer patients with color vision deficiency.
Researchers suggest several possible reasons:
-
Multiple early symptoms often appear in colorectal cancer, including abdominal pain and changes in bowel habits.
-
Routine screening programs, such as colonoscopy, detect many cases before symptoms appear.
-
Blood in stool is not always the primary presenting symptom, reducing reliance on visual detection.
These factors likely reduce the impact that color vision deficiency has on early disease recognition.
A Common but Often Undiagnosed Condition
Color vision deficiency is more prevalent than many people realize. It affects approximately 1 in 12 men and 1 in 200 women, with red-green colorblindness being the most common form.
Importantly, many individuals with colorblindness never receive a formal diagnosis. Because the study relied on medical records coded with ICD-10 diagnostic data, the true impact of color vision deficiency on cancer outcomes may actually be underestimated.
Implications for Clinical Awareness and Diagnostics
The findings raise important considerations for healthcare providers, diagnostic laboratories, and researchers studying disease detection pathways.
Potential strategies to reduce diagnostic delays may include:
-
Incorporating questions about color vision deficiency during clinical intake or screening
-
Encouraging routine urine testing during annual health checkups
-
Increasing patient education about non-visual symptoms associated with bladder cancer
-
Exploring diagnostic technologies that rely on biochemical markers rather than visual cues
For laboratory medicine and diagnostics professionals, the study also underscores the broader role of objective testing methods—such as urinalysis and molecular diagnostics—in identifying disease when subjective symptoms may be overlooked.
A Reminder That Diagnosis Can Be Multidimensional
This research highlights an often-overlooked aspect of medical detection: patient perception of symptoms. Biological variation in vision, hearing, or sensory perception can influence when individuals seek care and how diseases are identified.
By understanding these human factors, clinicians and researchers may be able to design more inclusive diagnostic pathways, ensuring that early warning signs are recognized regardless of sensory differences.
At Pro Lab Supply, we are proud to support the global community of scientists, clinicians, and laboratories advancing research, diagnostics, and healthcare innovation. Sharing discoveries like this helps foster collaboration and accelerate progress across the life sciences.
Source
Stanford Medicine. “Stanford scientists say colorblindness may hide a deadly bladder cancer warning.” ScienceDaily. March 10, 2026. (ScienceDaily)