Extracutaneous melanoma epidemiology in British Columbia.

The epidemiology of extracutaneous melanoma (ECM) is sparsely reported upon in the literature, and studies to date have been limited both by time and by geographic gaps in available data. Utilizing a comprehensive provincial cancer registry, we sought to analyze the incidence and survival rates of ECM on the basis of sex and anatomic distribution for the British Columbia, Canada population. Data on ECMs diagnosed between 1 January 1992 and 31 December 2006 were obtained from the BC Cancer Registry. Anatomical sites of ECM were classified on the basis of ICD-9 codes, and incidence rates for each site were age standardized and grouped by sex. The 5-year survival rate for each anatomical grouping was tracked until 31 December 2011. A total of 922 primary ECMs were recorded in the BC Cancer Registry between 1992 and 2006, representing 5.1% of melanoma incidence. Ocular melanomas were most frequently reported, with an age-standardized incidence rate (per million) of 10.6 for men and 8.5 for women. ECM patients were generally older at diagnosis and had poorer survival rates compared with cutaneous melanoma cases. Five-year survival rates for ECM varied markedly from 23.5% for genital lesions to 87.0% for ocular cases. Our ECM epidemiology results are largely consistent with previous studies from the USA and Europe. Where considerable differences in reported values do exist, the opportunity arises to assess the efficacy of melanoma detection, monitoring, and treatment strategies in different geographic regions. Our study represents the largest epidemiological investigation of ECM in Canada and provides a framework for future epidemiological comparisons.