Detecting blood in urine is often the first indication that something may be amiss in a person’s health, particularly regarding bladder cancer. Still, for individuals with colorblindness, recognizing this crucial warning sign can be significantly more challenging. A recent study from Stanford Medicine has revealed alarming findings: people diagnosed with bladder cancer who also have color vision deficiency may experience a 52% higher mortality rate over a 20-year period compared to those with normal vision.
The study, which analyzed an extensive set of health records, suggests that individuals with colorblindness are less likely to notice blood in their urine. They may delay seeking medical attention, leading to later-stage diagnoses when treatment is more complex and survival rates are significantly lower. “I’m hopeful that this study raises some awareness, not only for patients with colorblindness, but for our colleagues who notice these patients,” said Ehsan Rahimy, MD, adjunct clinical associate professor of ophthalmology and senior author of the study published in Nature Health.
The lead author of the research is Mustafa Fattah, a medical student at Columbia University Vagelos College of Physicians and Surgeons. This study highlights the intersection of color vision deficiency and cancer risk, emphasizing the importance of awareness among both patients and healthcare providers.
Understanding Colorblindness and Its Prevalence
Colorblindness, or color vision deficiency, is more common than one might think, affecting approximately 1 in 12 men and 1 in 200 women. The predominant forms of this condition challenge individuals’ ability to distinguish between red and green shades. This difficulty can lead to everyday issues, including interpreting traffic signals or assessing the color of raw meat.
Bladder cancer is notably more prevalent in men, who are diagnosed with the disease approximately four times more often than women. In 2025, an estimated 85,000 Americans were expected to receive a bladder cancer diagnosis. Previous studies have suggested that colorblindness could delay the diagnosis of various diseases, including bladder cancer. For instance, a 2009 study indicated that men with color vision deficiency were diagnosed at more advanced stages compared to those with normal color vision.
Research Methodology and Findings
The recent study utilized a vast research platform known as TriNetX, which aggregates real-time electronic health records from millions of patients worldwide. This extensive database allows researchers to identify specific groups of patients with rare combinations of health conditions.
In this study, the researchers focused on identifying patients diagnosed with both colorblindness and bladder cancer. From a pool of approximately 100 million U.S. Patient records, they found 135 individuals with both conditions and established a comparable control group of 135 patients with bladder cancer but normal vision. The findings revealed a significant disparity in survival rates, with the colorblind group experiencing a 52% higher overall mortality risk over two decades.
Comparative Analysis with Colorectal Cancer
Interestingly, the researchers anticipated observing a similar mortality pattern among patients with colorectal cancer and colorblindness. However, their analysis did not show a statistically significant difference between the two groups in this case. One potential explanation is that colorectal cancer typically presents with various early symptoms, such as abdominal pain and changes in bowel habits, rather than primarily with blood in stool.
In contrast, blood in urine is one of the most common early indicators of bladder cancer, often prompting immediate medical consultation. Studies indicate that between 80% and 90% of bladder cancer patients notice blood in their urine without accompanying pain, highlighting the distinct symptom presentation compared to colorectal cancer.
Implications for Medical Practice and Future Research
The study’s findings raise important questions regarding the need for additional research into how color vision deficiency may impact disease detection and patient outcomes. Ehsan Rahimy noted that many individuals with color vision deficiency may not have a formal diagnosis, leading to their being classified as having normal vision in health records. “Most people with color vision deficiency are typically functioning fine. They don’t have any other vision issues,” Rahimy pointed out.
This lack of awareness has already started discussions among medical professionals. Some urologists and gastroenterologists have acknowledged that they had never previously considered colorblindness as a factor in cancer diagnosis. Following these findings, there may be a shift toward incorporating questions about color vision deficiency in screening questionnaires.
For patients with color vision deficiency, the study underscores the importance of regular health check-ups. Healthcare providers often recommend routine urine tests during annual examinations, and individuals may want to enlist the help of a partner or family member to monitor for changes in urine color that could indicate potential health issues. “If you don’t trust yourself to know that there’s a change in the color of your urine, it could be worth having a partner or somebody you live with periodically checking it for blood, just to make sure,” Rahimy advised.
This research received funding from the National Institutes of Health and Research to Prevent Blindness, Inc., and it emphasizes the critical intersection of vision health and cancer awareness.
As further studies are conducted, it will be essential to explore the implications of these findings more deeply, potentially leading to improved screening protocols and greater awareness among healthcare providers regarding the unique challenges faced by patients with color vision deficiencies.
For individuals affected by color vision deficiency, maintaining routine health checks and advocating for awareness in medical settings can be crucial steps in ensuring timely interventions for serious health conditions.
