Abstract
Abstract: :
Purpose:On a population–level establish the risk of secondary malignancies following the diagnosis of uveal melanoma, compared to the expected rates in the Swedish population. Association between cancers might indicate shared risk factors or a similar etiology. Methods:The Swedish Cancer Registry, with an inclusion rate of >95% of the cancer cases revealed 2995 uveal melanoma patients during the period 1960–98. The secondary cancers occurring after the diagnosis of uveal melanoma were identified through the files in the Cancer Registry, using the ICD–7 and histolgy code. The expected numbers of invasive cancers, calculated as person–years at risk was estimated according to the incidence rates in the general Swedish population with respect taken to gender, age and calendar period. Cancer sites with five or more expected cases were analyzed with standardized incidence ratios (SIR) or if the observed number of cases remarkedly differed from the expected number. The SIR was calculated by dividing the observed number of cancer cases with the expected. The 99% confidence intervals (CI) were estimated, assuming a Poisson distribution of the observed cases. Results:During the period 1960–1998 the uveal melanoma patients in the Swedish Cancer Registry accumulated 24.847 person–years of observation. Of the 2995 patients with uveal melanoma, 343 (11.5%) had registrations of a second primary invasive cancer. The cancer sites were collapsed into the major ICD–7 groups, the observed and expected numbers presented in Table 1, along with the standardized incidence ratios. Conclusions:Swedish uveal melanoma patients were found to have a 21% increased risk of developing a second cancer compared to the general population. Cutaneous melanomas were twice as common as expected. In contrast, non–melanoma skin cancer where UV–radiation also is a risk factor had a SIR 32% below the expected. This could indicate that shared risk factors for the uveal and cutaneous melanoma exists, but the role of UV–radiation still remains controversal. Cancer cases secondary to uveal melanoma in the Swedish population.
Keywords: oncology • tumors • uvea