At a Glance
- Colorblindness may heighten the risk of dying from bladder cancer.
- In a 20-year study, color-blind patients had a 52% higher mortality rate.
- No survival difference was seen for colorectal cancer.
- Why it matters: The findings suggest clinicians should consider early screening for bladder cancer in color-blind patients.
Colorblindness could be a hidden risk factor for bladder cancer, a new study suggests. Researchers compared cancer outcomes in people with and without color vision deficiency and found a striking difference in survival for bladder cancer. The study, published this month in Nature Health, raises questions about how color perception may affect early cancer detection.
Background on Colorblindness
Colorblindness, or color vision deficiency, affects about 8% of men and 0.5% of women. The condition stems from genetic mutations that alter the function of cone cells in the retina. These cells normally detect blue, red, and green light; when they malfunction, patients often cannot distinguish between red and green hues.
Because many early signs of bladder cancer-such as blood in the urine-appear as a reddish color, color-blind individuals may overlook these warning signs. While colorectal cancer can also present with blood in stool, other symptoms like chronic diarrhea or constipation often prompt earlier medical attention.
Study Design and Cohort
The researchers accessed a large electronic health record database and identified:
| Cancer Type | Color-Blind Participants | Non-Color-Blind Controls |
|---|---|---|
| Bladder | 136 | Comparable group |
| Colorectal | 187 | Comparable group |
Both groups were matched for age, sex, and other demographic factors. The analysis spanned 20 years, tracking overall mortality rates.
Key Findings
- Bladder cancer: Color-blind patients had a 52% higher risk of death compared to non-color-blind patients.
- Colorectal cancer: No significant survival difference was observed.
The authors noted that the lack of difference in colorectal cancer may be due to other early symptoms that prompt medical evaluation before the disease progresses.
> “I’m hopeful that this study raises some awareness, not only for patients with colorblindness, but for our colleagues who see these patients,” said senior study author Ehsan Rahimy, adjunct clinical associate professor of ophthalmology.
Possible Explanations
- Missed visual cues: Blood in urine is a red color; color-blind individuals may not perceive it.
- Symptom awareness: Colorectal bleeding can be accompanied by other noticeable changes, reducing diagnostic delay.
- Screening practices: Routine colorectal screening begins at age 45, which may mitigate delays for color-blind patients.
The researchers caution that their work is hypothesis-generating and does not establish a direct causal link. They also advise against immediate changes to clinical guidelines.
Implications for Clinicians
The study authors recommend:
- Heightened diagnostic suspicion for bladder cancer in patients with color vision deficiency.
- Further research into whether targeted screening for bladder cancer could benefit high-risk color-blind individuals.
> “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,” the authors wrote.
Take-Away Points
- Colorblindness may increase bladder cancer mortality.
- No survival difference was found for colorectal cancer.
- The findings underscore the need for awareness among both patients and clinicians.
- Further studies are required to determine if screening protocols should be adapted.
By recognizing the unique challenges faced by color-blind patients, healthcare providers can work toward earlier detection and improved outcomes.
