Study suggests adverse impact of color blindness on bladder cancer survival

medwireNews: Among people with bladder cancer, those with color vision deficiency have significantly poorer overall survival than those with no such deficiency, suggests a database analysis reported in Nature Health.

The researchers postulate that this could be because “patients with [color vision deficiency] are more likely to delay seeking care for cancers with blood in urine or stool as a presenting symptom, leading to more invasive disease on initial presentation” and therefore worse survival.

Of note, they found no such association between color vision deficiency and worse survival among people with colorectal cancer (CRC).

But the team points out that “whereas bladder cancer tends to present with painless haematuria (meaning, the only sign of disease is blood in the urine), colorectal cancer can often present with a multitude of other symptoms that may indicate disease even in a patient who cannot see blood in the stool.”

For the study, the investigators drew on the TriNetX Health Research Network to identify individuals who were diagnosed with bladder cancer between January 2004 and March 2025, of whom 149 had color vision deficiency and 371,154 did not. The corresponding numbers for CRC were 216 and 757,629.

After applying propensity score matching, the cohorts comprised 135 bladder cancer patients with color vision deficiency and an identical number without (mean age 71.9 and 70.6 years, respectively; 92.6% men), and 187 CRC patients with and without color vision deficiency (mean age 65.2 and 66.7 years, respectively; 70.1% women).

A log-rank analysis showed that bladder cancer patients with color vision deficiency had a significantly lower survival probability than their counterparts without such a deficiency (Χ²=4.85), whereas there was no such significant association in the CRC cohort.

Further analysis of the bladder cancer cohort revealed that the 20-year mortality rate was a significant 52% greater for individuals with versus those without color vision deficiency.

Discussing the results, Ehsan Rahimy (Stanford University School of Medicine, Palo Alto, California, USA) and co-researchers say that “[w]hile incorporating staging data into our analysis would have offered a clearer window into the biological underpinnings of our findings,” it was not possible because not all healthcare organizations contribute this information to the TriNetX system.

However, “the existing literature offers support for the mechanism we propose, namely that patients with [color vision deficiency] seek care later and thus present with more advanced cancer, placing them at higher risk of mortality,” they continue.

And the researchers conclude: “This is a hypothesis-generating paper that should raise clinicians’ diagnostic suspicion for bladder cancer in patients with [color vision deficiency] and prompt further investigation into whether screening for bladder cancer should be introduced for high-risk individuals with [color vision deficiency].”

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2026 Springer Healthcare Ltd, part of Springer Nature

Nat Health 2026; 1: 113–119