Color vision deficiency (CVD) may influence detection of cancers that present with visible blood, with data suggesting reduced survival in patients with bladder cancer and CVD.
Bladder and colorectal cancers often present with blood in urine or stool. Recognition of these signs is a common trigger for clinical evaluation. However, individuals with CVD – an inherited condition that affects the ability to distinguish colors, particularly red – may have difficulty identifying these symptoms. CVD affects approximately one in 12 males and one in 200 females.
In this retrospective cohort study, investigators used the TriNetX electronic health records network to compare outcomes in patients with bladder or colorectal cancer, with and without documented CVD. Cohorts were matched using propensity score methods to control for demographic and clinical variables.
Among patients with bladder cancer, 135 individuals with CVD were matched to 135 controls. Kaplan–Meier analysis showed lower overall survival in the CVD group. A separate 20-year analysis found higher mortality in patients with CVD.
In contrast, no significant difference in survival was observed in colorectal cancer. Among 187 matched pairs, survival did not differ between patients with and without CVD.
Differences between cancer types may reflect clinical presentation. Bladder cancer commonly presents with painless hematuria, which may be the only early symptom. Colorectal cancer more often presents with additional features, such as abdominal pain or changes in bowel habits, and is also subject to routine screening.
Previous reports cited in the study describe delayed care-seeking in patients with CVD who misinterpret blood in stool or urine. Experimental data also show reduced accuracy in identifying blood in biological samples among individuals with CVD.
These findings indicate that impaired recognition of visible blood may contribute to delayed presentation in bladder cancer. The study also notes that CVD is often undiagnosed and not routinely assessed in clinical practice.
Limitations include reliance on diagnostic coding within electronic health records and limited availability of staging data, which restricts assessment of disease severity at presentation.
Overall, the study highlights a potential diagnostic gap related to visual impairment that may affect detection pathways in bladder cancer, with less impact observed in colorectal cancer.
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