The risk of other primary cancer in patients with uveal melanoma: a retrospective cohort study of a Canadian population.

Background: The incidence of second primary malignant tumours has doubled during the last 2 decades. These tumours now represent the sixth most common group of cancers. Many authors have described the presence of multiple primary cancers in patients with uveal melanoma. However, no studies have been performed using Canadian data. The purpose of this study was to describe the occurrence of other primary cancers diagnosed before or after uveal melanoma and to calculate the incidence of subsequent primary cancer in a Canadian cohort with uveal melanoma.

Methods: We conducted a retrospective study of a cohort of patients with uveal melanoma diagnosed between 1990 and 2002 at a university-affiliated centre in Montreal. We reviewed medical records to identify patients in whom other, unrelated primary malignant disease had been diagnosed. We used the standardized incidence ratio to calculate the risk of development of a second, unrelated cancer following the diagnosis of uveal melanoma.

Results: A total of 129 cases of uveal melanoma were diagnosed. Eighteen patients (14%) also had a diagnosis of an unrelated primary cancer. In nine patients the other cancer had been diagnosed first, and in nine patients the other tumour had been diagnosed after the uveal melanoma. There was no increased risk of development of any particular form of cancer studied for females or males.

Interpretation: In our Canadian cohort, statistical analysis showed no increased risk of a second cancer, overall or by organ site, in male or female patients with uveal melanoma. As uveal melanoma is a rare type of cancer, analyses of a much larger cohort may be needed to accurately estimate the risk of development of a second primary cancer in patients with uveal melanoma.