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Risk factors for intraocular melanoma and occupational exposure

Ocular melanoma is an uncommon cancer. Age standardised incidence ranges from 0.4 to 1.2 cases per 100 000 within Europe and from 0.1 to 2.3 worldwide (figures from WHO and International Agency for Research on Cancer (IARC)). Only one report1 suggests any change over decades.2-6 However, incidence data from the USA show a decrease over the period 1973–89.7 

The behaviour of intraocular melanoma varies with site. Tumours located in the iris form 10% of eye melanomas8 and usually have low grade histology with a good prognosis.9 Local excision is effective in most such cases although some may require enucleation, and metastasis is seen in only 3% of cases. In contrast, melanoma of choroid or ciliary body has a poor prognosis, although late metastasis after removal of the primary tumour is common. Metastasis is haematogenous and 1 year survival after liver metastasis not higher than 10%.10 Raivio8 in Finland observed that survival rates at 5, 10, and 15 years were 65%, 52%, and 46% respectively. Among the 12% of patients surviving at least 20 years, 21% developed metastasis thereafter. Treatment of metastatic disease by chemotherapy has been disappointing with less than 1% response rates to systemic DTIC based chemotherapy.11 Prognosis therefore reflects the development of metastasis uninfluenced by treatment, although recent developments hold some hope of progress.12 13 

Twenty years ago “many of the difficulties in diagnosing choroidal melanomas which clinicians confronted in the past [had] been eliminated”.14 15 The past two decades have seen advances in classification, now widely accepted,16 and continuing refinement of prognostic factors influencing outcome in these patients.17-20 However, despite a number of studies of risk factors for intraocular melanomagenesis, the cause of this tumour is far from clear.

During the 1980s, with increased interest in …