A nationwide study in Denmark has demonstrated an increased incidence of cancer in patients with retinal vein occlusion (RVO) compared with age-and gender-matched controls. However, the types of cancer detected in patients with RVO were not different from the types found in controls, and the excess risk seemed to be of stable magnitude over time from RVO diagnosis.

The relationship between RVO and cancer isn’t causal—but is it germane to an eye doctor’s patient counseling responsibilities? This study didn’t address that question, though it will be on the minds of optometrists and ophthalmologists alike.

Researchers assessed 7,963 patients ages 61 to 79 without cancer at the time of the first RVO diagnosis, and a control cohort of 39,815 individuals with the same age and gender distributions. The study followed all patients for five years or until either a diagnosis of cancer or death. The analysis revealed an RVO diagnosis was associated with a 22% increased risk of being diagnosed with cancer, and the study authors note adjusting for age, gender and calendar year did not affect the association.

While adjusting for comorbidities reduced the strength of the association, it remained significant. At baseline, comorbidities were more frequently present in the RVO cohort. The distributions of cancer types in RVO patients and controls were similar, while rates of cancer and death within one and three years, respectively, were higher in the RVO cohort.

The researchers believe their study suggests the association is mainly due to shared risk factors. They did not find a peak in cancer incidence immediately after the RVO diagnosis, nor that hematological cancers made up a larger percentage of the total number of cancers in RVO patients. That occurrence would likely have been the case if a systemic coagulopathy or a hyperviscosity syndrome provoked the RVO. The study concluded that future research should evaluate the benefit of risk factor identification and modification in RVO patients.