People who are colorblind may be missing a life-saving warning sign of bladder cancer. Analysis of the electronic health records of hundreds of people found that those with color vision deficiency (CVD), or color blindness and bladder cancer had significantly worse outcomes than patients with normal vision, according to a study published in Nature Health.
Warning signs may go unnoticed
Bladder cancer is a major health concern and one of the most common cancers worldwide, according to the World Health Organization (WHO). For many individuals, the first warning sign is blood in their urine. However, people with color blindness may miss this early clue that something is wrong because they struggle to distinguish red from shades of brown or green. The study authors suspected that this blind spot in cancer detection leads to dangerous delays in seeking care.
To determine whether this was the case, the team analyzed data from the TriNetX electronic health records network. This is a massive global database of anonymous medical files.
The researchers compared 135 colorblind patients with bladder cancer to a group of 135 patients with the same condition but normal vision. Each pair had the same age, race, sex and even the same health histories, such as diabetes or high blood pressure. They also compared 187 matched pairs with colorectal cancer.
Increased risk
The researchers found that over a 20-year period, the CVD group experienced a 52% higher risk of death compared to the non-CVD group. According to the study, the possible explanation for this is not any difference in cancer biology, but the nature of the disease itself.
Bladder cancer is usually painless at first, meaning the red color of blood is often the only early warning a person receives. If someone doesn’t feel any pain and cannot see the color, they may not know anything is wrong until later, when the cancer has invaded deeper tissues and becomes harder to treat.
For colorectal cancer, there was no significant difference in survival between the two groups. The researchers believe this is because colorectal cancer is often caught through screening or because some symptoms are felt, such as stomach pain.
The study authors point out that their conclusions are not definitive proof but rather a starting point for more research. Even so, these findings could change the ways doctors treat colorblind patients, as they comment in their paper: “These hypothesis-generating findings should increase clinicians’ suspicion of bladder cancer among patients with CVD and nonspecific signs of malignancy.”
A News & Views article on the research is also published in Nature Health.