Color Blindness Could Delay Bladder Cancer Detection, Study Finds

• What happened: New research shows that people with color blindness may miss early warning signs of bladder cancer, specifically blood in urine, leading to delayed diagnosis.

• Why it matters now: Delays in spotting symptoms can reduce survival rates for color-blind patients compared with those with normal color vision.

• What changes for people: Color-blind individuals should report urinary changes promptly and doctors may need to investigate symptoms more proactively.

• Who is affected: Men are disproportionately affected, as both bladder cancer and red-green color blindness are more common in males.

A new study published in Nature Health highlights a hidden risk for people with color vision deficiency: missing early signs of bladder cancer. Researchers analyzed records from over 275 million people worldwide, focusing on patients with bladder cancer. They found that patients with color blindness had a 52% higher risk of death over 20 years compared to matched individuals with normal color vision.

The primary reason is simple yet critical: impaired perception of red makes it harder to notice blood in urine, the first and often painless symptom of bladder cancer. Delayed recognition can allow the disease to progress to a more advanced and harder-to-treat stage.

Interestingly, the study also checked colorectal cancer, which can cause blood in stool. Researchers found no difference in survival between color-blind and non-color-blind patients, likely because routine screening catches colorectal cancer early, whereas bladder cancer has no standard screening for asymptomatic individuals.

Bioengineer Mustafa Fattah of Columbia University, who co-led the study, explained: “Impaired perception of red is really the driving force here.” Family medicine specialist Masahito Jimbo added, “Clinicians should have a low threshold to investigate urinary symptoms in color-blind patients.”

Bladder cancer is common in the U.S., with around 80,000 new cases annually, and men are most affected. Similarly, red-green color blindness occurs in about 1 in 12 men, making this a significant public health concern.