Patients with retinal vein occlusion (RVO) have an increased risk of developing cancer, even after adjusting for demographic factors and comorbidities, according to a newly published retrospective cohort study in the British Journal of Ophthalmology.
To investigate the association between incident RVO and the subsequent development of cancer, researchers looked at South Korea’s 2002–2013 National Health Insurance Service database. Using this data, 186,701 RVO patients and their 1:1 propensity-score matched controls were included in the study. The fixed cohort for the study included patients seen between January 1, 2004, and December 31, 2013, and those who suffered incident RVO after entering the cohort. Patients with any history of cancer prior to entering the cohort were excluded.
To assess the association of RVO and cancer, researchers applied time-varying covariate Cox regression models. Model 1 included RVO as a time-varying covariate, Model 2 included Model 1 plus demographic information, and Model 3 included Model 2 and comorbidities.
Using this analytical approach, the team found that RVO was associated with an increased risk of subsequent cancer (HR=1.29; 95% CI, 1.26–1.31 in Model 1), which also was consistent in Models 2 and 3. The incidence rate of overall cancer during the study period was 25.55 (95% CI, 25.19–25.91) per 1000 person-years in the RVO group and 18.62 (95% CI, 18.46–18.79) per 1000 person-years in the control group.
The investigators noted that cancers in the cohort occurred in lips or oropharynx, stomach, colon, liver or biliary tract, lung, bone or joint cartilages, skin, mesoderm or soft tissue, ureter, eye, brain or central nervous system, thyroid or other endocrine organs, lymphoid or hematopoietic cells, ovaries, and prostate. Although RVO subjects faced greater risk for all cancers, the risk varied by each organ-specific cancers, suggesting that the association with RVO may vary by organs. In fact, in some organs (esophagus, nasal cavities and middle ear, nasal sinuses, larynx, trachea, thymus, breasts, cervix, and uterus) the researchers noted no statistical significance.
Because previous studies had suggested that the association between RVO and cancer may be due to shared risk factors—instead of a causal relationship—the researchers used propensity scores to ensure that the possible confounders (sex, age, residential area, household income, and comorbidity) in the control group were similar to those in the incident RVO group. This enabled them to match the controls who had comparable characteristics in demographics and comorbidity to those for the incident RVO group. They also performed a Cox regression analysis of demographics and comorbidity.
The investigators point out that most RVO patients do not receive extensive medical workups or cancer screenings. “According to the American Academy of Ophthalmology guidelines for RVO, optimizing control of systemic arterial hypertension, diabetes, serum lipid levels, and intraocular pressure to control glaucoma are all important in the management of systemic risk factors; however, clear guidelines on systemic testing are lacking,” according to the researchers.
Further study is needed to determine appropriate cancer screening recommendations for patients with RVO based on these findings.
This study was subject to several limitations, including that the team analyzed a database of medical claims, not hospital-based medical records, which prohibited them from validating the diagnosis of RVO for each patient. Second, the researchers explain that there may be unknown confounders between RVO cases and cancers. Lastly, they did not perform separate analyses for central RVO and branch RVO.
Kim MS, Cho JH, Byun SJ, et al. Increased risk of cancer in patients with retinal vein occlusion: a 12-year nationwide cohort study. Br J Ophthalmol. Published OnlineSeptember 26, 2020. doi: 10.1136/bjophthalmol-2020-316947.