Color vision deficiency is an inherited condition affecting 1 in 12 males (8%) and 1 in 200 females (0.5%), most often impairing the ability to distinguish the color red. A recent study published in Nature Health examined the possible impact of color vision deficiency on survival outcomes among patients with bladder or colorectal cancer. Led by Fattah et al, the investigation explored the hypothesis that patients with color vision deficiency may experience delayed cancer detection because they are less able to recognize blood in their urine or stool—often an early warning sign of these malignancies—potentially leading to worse clinical outcomes.
Study Details
The researchers used data from the TriNetX Health Research Network (from January 2004 to March 2025) to compile patient cohorts based on their diagnoses of bladder cancer, colorectal cancer, and color vision deficiency (or the absence thereof). Propensity score matching was done to balance the cohorts for age at cancer diagnosis, sex, race, ethnicity, and various comorbidities, including hypertension and diabetes. For the primary analysis, 135 patients with bladder cancer and color vision deficiency were matched 1:1 with 135 patients with bladder cancer without color vision deficiency. Similarly, 187 patients with colorectal cancer and color vision deficiency were matched with 187 control patients without color vision deficiency. The primary outcomes were overall survival probability and, when appropriate, 20-year mortality risk.
Key Results
Kaplan-Meier analysis demonstrated a lower survival probability among patients with bladder cancer in the color vision deficiency cohort, with a statistically significant difference observed on log-rank testing (P = .028). In a subsequent 20-year mortality analysis, patients with bladder cancer and color vision deficiency experienced a 52% higher risk of death compared with controls (risk ratio = 1.52, 95% confidence interval = 1.05–2.19, P = .025).
In contrast, no significant differences in overall survival were observed between patients with colorectal cancer with color vision deficiency and those without color vision deficiency. Survival curves for these two cohorts were similar, and the absence of a statistically significant difference precluded further long-term mortality analysis.
The study authors noted that these divergent findings may reflect differences in disease presentation and screening practices. Bladder cancer tends to present with painless hematuria as the sole early symptom, placing greater reliance on visual detection by the patient. Colorectal cancer, by comparison, often presents with additional symptoms such as abdominal pain, changes in bowel habits, or weight loss and is also subject to routine population-based screening, which may mitigate the impact of impaired color recognition.
The investigators concluded that color vision deficiency may represent an underrecognized risk factor for reduced survival among patients with bladder cancer, but not colorectal cancer. They emphasized the need for heightened clinical awareness and further research to determine whether targeted screening strategies could improve outcomes in this population.
“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],” they stated.
Ehsan Rahimy, MD, of the Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, is the corresponding author for the Nature Health article.
DISCLOSURE: The study was funded by P30 Vision Research Core and Research to Prevent Blindness. For full disclosures of the study authors, visit nature.com.
