Color blindness may hide an early bladder cancer warning

A study found people with color vision deficiency were more likely to be diagnosed with bladder cancer at later, more invasive stages and had a higher long-term risk of death compared with those with normal color vision.

A recent study suggests color vision deficiency can mask one of the only early warning signs of bladder cancer. The research compared health records to see whether people with color blindness had different outcomes. Blood in the urine is often a painless early sign of bladder cancer, and difficulty distinguishing red tones can make that symptom harder to notice. Researchers and external experts said the findings merit further study and awareness. Key findings: - Color blindness affects about 1 in 12 men and 1 in 200 women worldwide. - The study compared 135 people with both bladder cancer and color blindness to 135 people with bladder cancer alone. - Patients with color vision deficiency were more likely to be diagnosed at advanced, invasive stages and had a 52% higher risk of dying within 20 years compared with the normal-vision group. - The authors noted that blood in urine is often an early, painless sign and that there is no routine screening recommendation for asymptomatic bladder cancer, unlike colorectal cancer. Summary: The study links color vision deficiency to later-stage bladder cancer diagnoses and higher long-term mortality among those included in the analysis. Researchers acknowledged limitations, including that color blindness is often undetected, and said further investigation is warranted. Undetermined at this time.