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Color blindness hides a key warning sign of bladder cancer

New research links impaired color vision to delayed diagnosis and lower survival

A clinician shows a patient a color vision test book during an eye exam at a desk.

Color blindness may hide one of bladder cancer’s earliest warning signs: blood in urine.

rudi_suardi/E+/Getty Images

By Elie Dolgin

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For most people with bladder cancer, the first red flag is literally red: blood in the urine.