Health: Colour vision deficiency may worsen bladder cancer outcomes (Nature Health)
16 January 2026
People with bladder cancer who are also colour blind may have a lower chance of survival than those with normal colour vision, according to research published in Nature Health. The study suggests that doctors might need to pay closer attention to this group and consider whether extra screening could improve survival outcomes.
Bladder and bowel cancers are among the most common cancers, and one of the earliest warning signs is blood in urine or stool. However, for people with colour vision deficiency — a condition that makes it difficult or impossible to see certain colours, especially red — this sign can be easy to miss. If blood goes unnoticed, diagnosis and treatment may be delayed.
Ehsan Rahimy, Mustafa Fattah and colleagues compared the outcomes of patients with bladder or colorectal cancer with and without colour vision deficiency. Among 135 patients with bladder cancer and colour vision deficiency and 135 control participants (with bladder cancer but full colour vision), the bladder cancer cohort with colour vision deficiency had a lower survival probability and a 52% higher chance of dying in the 20 years after receiving a diagnosis. By contrast, there was no significant difference in survival between 187 patients with colorectal cancer and colour vision deficiency and 187 control patients.
The authors suggest that this difference may be because bladder cancer often shows no symptoms other than blood in the urine, whereas bowel cancer can cause other signs such as pain or changes in bowel habits. They note some limitations, including the possibility that many people with colour vision deficiency are never officially diagnosed with the impairment. Future research should validate these results and explore whether screening high-risk populations with colour vision deficiency for bladder cancer improves survival outcomes.
- Article
- Published: 15 January 2026
Fattah, M., Alsoudi, A.F., Mruthyunjaya, P. et al. Impact of colour vision deficiency on bladder and colorectal cancer survival. Nat. Health 1, 113–119 (2026). https://doi.org/10.1038/s44360-025-00032-7
News & Views: Colour blindness as a risk factor for bladder cancer
https://www.nature.com/articles/s44360-025-00029-2
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