Cancer and Oncology

A new study in the journal Nature Health from Stanford Medicine finds that bladder cancer patients who are also colorblind face a 52% higher mortality risk over 20 years than patients with normal color vision, likely because they miss blood in their urine — the most common early warning sign of the disease. Color vision deficiency affects an estimated 8% of men and 0.5% of women, and most cases involve difficulty distinguishing red and green, the colors critical for noticing blood in urine. Lead author Dr. Ehsan Rahimy said the results should alert both patients and clinicians that colorblindness can delay care even though it does not cause cancer itself. Outside experts quoted in the piece say doctors may overlook this detail in medical histories and urge colorblind patients to tell providers about their condition and to seek evaluation if their urine ever looks abnormal rather than relying on color alone. The findings are particularly relevant in the U.S., where bladder cancer is about four times more common in men than women and where early detection significantly improves outcomes.