Risk of non-Hodgkin's lymphoma and skin malignancies in patients diagnosed with cataract.

The rapid increase of non-Hodgkin's lymphoma (NHL) in industrialized countries is yet unexplained. Ultraviolet radiation (UVR) has been suggested as an aetiologic factor due to observed elevated risks of cutaneous malignancies after NHL and vice versa. Cataract, as related to UVR, was tested as a proxy variable to further elucidate this observation. Cataract in-patients (n = 49914) reported to the Swedish Patient Register and later developing NHL and cutaneous malignancies were identified by record linkage to the Swedish Cancer Registry. The observed number of malignancies among cataract patients did not differ significantly from that expected in the general population. In contrast, the risk of cutaneous malignant melanoma was lower than anticipated, based on Swedish background incidence figures. The results did not give support for a causal relationship between NHL and UVR.