Bladder cancer is one of the most common cancers in the world. For many people, the first warning sign is seeing blood in their urine.
But a new study suggests that people who are colorblind may not notice this important early sign—and that could be life-threatening.
The research was published in the journal Nature Health. It found that people with color vision deficiency (CVD), also known as colorblindness, had worse outcomes when they developed bladder cancer compared to people with normal vision.
People who are colorblind have trouble telling some colors apart. Most often, they cannot clearly see the difference between red and colors like brown or green. This could be a big problem when it comes to spotting blood in urine, which is often a key warning sign of bladder cancer.
The authors of the study believed that colorblind people may miss this signal and wait longer to see a doctor, which could make the disease harder to treat.
To find out more, the researchers looked at a huge medical database called TriNetX. This database includes anonymous medical records from around the world. They compared 135 people with colorblindness and bladder cancer to 135 people with bladder cancer and normal vision.
These pairs were carefully matched. They had the same age, race, sex, and health conditions like diabetes or high blood pressure. The researchers also looked at 187 matched pairs of people with colorectal cancer to see if the same problem existed.
The results were striking. Over 20 years, people with colorblindness and bladder cancer had a 52% higher risk of dying compared to people with normal vision. The researchers believe the reason is not that their cancer was different, but because they didn’t notice the blood in their urine early enough.
Since bladder cancer often doesn’t cause pain at first, the color change in urine can be the only early clue that something is wrong. If a person cannot see that color change, they may not seek help until the cancer has spread and become harder to treat.
Interestingly, the study did not find the same risk difference in people with colorectal cancer. That’s likely because colorectal cancer is often caught through routine screening or because it causes symptoms like stomach pain.
The researchers say their results are not final proof, but they should raise awareness. They hope that doctors will be more alert when treating colorblind patients who show any unclear signs of cancer. The authors wrote that doctors should have a higher level of suspicion for bladder cancer in patients with colorblindness who report unusual symptoms.
This study could lead to changes in how cancer is diagnosed in people with color vision problems and may help save lives by encouraging earlier testing.
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