Incidence of squamous-cell carcinoma of the conjunctiva and other eye cancers in the NIH-AARP Diet and Health Study

PURPOSE To investigate the risk factors for squamous-cell carcinoma of the conjunctiva (SCCC) and other eye cancers in the NIH-AARP Diet and Health Study. METHODS We estimated incidence rates and associations with age, sex, race/ethnicity and ultraviolet radiation using Cox proportional hazards models. RESULTS The incidence was 37.3 per 10(6) for all eye cancers (N = 178), 8.4 per 10(6) for SCCC (N = 40) and 28.9 per 10(6) for other eye cancers (N = 138). For all eye cancers, the incidence was lower in women than in men (hazard ratio [HR] = 0.38, 95% CI: 0.26, 0.55) and in persons aged ≤60 years than those aged >60 years (HR = 0.51, 95% CI: 0.36, 0.72). The incidence was higher, but not statistically significant, in those with an average net erythemal exposure >170 versus ≤170 (HR = 1.19, 95% CI: 0.88, 1.63) and lower in those residing at latitudes >35° versus ≤35° (HR = 0.81, 95% CI: 0.61, 1.09). The patterns were similar for SCCC in sex, age, race/ethnicity and average net erythemal exposure, but not statistically significant. CONCLUSION The incidence of all eye cancers was associated with male sex and older age. The same patterns were observed for SCCC. The associations reported here might be surrogates of exposure to ultraviolet radiation, although more follow-up is needed to obtain precise results.