According to the journal Nature Health, scientists' analysis of long-term follow-up results for bladder cancer patients showed that the risk of death was significantly higher among those with tumors who also suffered from color vision deficiency. This suggests a need to change the screening strategy for this type of tumor and encourages doctors to conduct regular screening tests for patients with color blindness.
These findings were reached by a team of American ophthalmologists and oncologists, led by Dr. Ehsan Rahimi, Associate Professor at Stanford University, during a study of the medical records of a large number of cancer patients who were treated in different clinics in the United States between January 2004 and March 2025. The study included patients with bladder and rectal cancer, some of whom suffered from color blindness, which prompted the researchers to study the effect of this visual impairment on patient outcomes.
The researchers explained that their interest in color blindness stems from the fact that blood in the stool or urine is one of the first signs of colorectal and bladder cancer . This symptom often prompts a doctor's visit, allowing for early detection of tumors. However, individuals with color blindness may not notice traces of blood, leading to late tumor detection and reducing their chances of treatment and survival.
The study compared 135 cancer patients of the same age, sex, and medical history, some of whom were colorblind. Researchers compared mortality rates over two decades, along with tumor complications. The results showed that colorblindness did not affect the course of the disease in colorectal cancer patients, but it increased the risk of death by 52% in bladder cancer patients over a 20-year period. The researchers emphasize the need for more comprehensive screening for early detection in colorblind individuals and for further studies to understand the statistical relationship.
According to the International Agency for Research on Cancer (IARC), approximately 1.6 million people worldwide suffer from bladder cancer , with about 570,000 new diagnoses each year, while another 200,000 die from complications related to tumor progression. When the disease is detected in its early stages, 63–98% of patients survive, while the development of metastases reduces this rate to 5–35%.
