Ocular melanoma is a rare neoplasm with a poorly understood etiology, especially concerning its link with ultraviolet-light exposure. Studying the risk of second primary cancers may help to formulate causal hypotheses. We used data from 13 cancer registries, including 10,396 first occurring ocular melanoma cases, and 404 second occurring cases. To compare the second cancer incidence in ocular melanoma patients to that in noncancer population, we calculated standardized incidence ratios (SIRs) of 32 types of cancer. We also calculated SIRs of second ocular melanoma after other primaries. Ocular melanoma patients had significantly increased risk of cutaneous melanoma (SIR 5 2.38, 95% CI 1.77-3.14), multiple myeloma (SIR 5 2.00, 1.29-2.95), and of liver (SIR 5 3.89, 2.66-5.49), kidney (SIR 5 1.70, 1.22-2.31), pancreas (SIR 5 1.58, 1.16-2.11), prostate (SIR 5 1.31, 1.11-1.54), and stomach (SIR 5 1.33, 1.03-1.68) cancers. Risks of cutaneous melanoma were highly variable between registries and were mainly increased in females, in younger patients, in first years following diagnosis, and for patients diagnosed after 1980. The risk of ocular melanoma was significantly increased only after prostate cancer (SIR 5 1.41, 1.08-1.82). Risk of cutaneous melanoma after ocular melanoma had epidemiological patterns, similar to cutaneous melanoma screening in the general population. The increased risk of cutaneous melanoma would be largely due to greater skin cancer surveillance in ocular melanoma patients, and not to common etiological factors. The high SIR found for liver cancer may be explained by misclassification bias. Common etiological factors may be involved in ocular and prostate cancers. ' 2006 Wiley-Liss, Inc.Key words: ocular melanoma; second primary cancers; registry-based study Cancer of the eye is a relatively rare neoplasm with an estimated incidence of less than 10 per million in most countries.1 Ocular melanoma is the most frequent primary intraocular tumor in adults, and the eye is the commonest site for noncutaneous melanoma, accounting for approximately 60% of such lesions.2 It is often a fatal disease, with a five-year mortality rate of 25%.2 Ocular melanoma is far more common in lightly pigmented people: the incidence was 6.02 per million in US white population for 0.31 in Blacks, 0.38 in Asians and 1.67 in Hispanic.
3Studying associations between ocular melanoma and other cancers may help to formulate etiological hypotheses, and shared risk factors may be suspected when association is symmetrical, i.e., a specific cancer more frequently found after an ocular melanoma is also more frequently found as preceding ocular melanoma. 4 The few studies that examined cancer occurrence after ocular melanoma included relatively low numbers of ocular melanoma or did not investigate the occurrence of ocular melanoma after another cancer. 5,6 We report here the results of a pooled analysis of data from 13 population-based cancer registries on second primary cancers in ocular melanoma patients, aiming at investigating the ...