Unique Geospatial Accumulations of Uveal Melanoma.

PURPOSE

The main purpose of this paper was to describe the unique accumulation of cases of uveal melanoma (UM). All patients were white and did not have known occupational risk factors. From the authors' standpoint, there were no lifestyle factors in common in the reported cases. Results of more extensive analyses, including geospatial analysis, are currently being conducted and will be presented in a separate paper.

DESIGN

Observational case series.

METHODS

Descriptive data from medical records, patient interviews, and questionnaires were obtained from 5 patients from North Carolina, 6 patients from Alabama, and 14 patients from New York. Standard incidence ratio (SIR) calculations were provided by the respective states' cancer registries. UM is the most common primary malignant eye tumor in adults, although it is rare, with 2,500 cases diagnosed annually in the United States. Despite a growing understanding of the molecular characteristics, there remains uncertainty regarding epidemiologic trends and environmental risk factors. This study identified 3 geographic accumulations of UM: 1) Huntersville, NC; 2) Auburn, AL; and 3) Broome and Tioga Counties, New York. Investigation of these groups will guide ongoing efforts to discover potential risk factor and assist with future treatment and prevention.

RESULTS

In North Carolina, 5 females who were identified as living in Huntersville, NC, were diagnosed with UM at ages 20, 22, 24, 30, and 31. The SIR calculations considering the observed and expected incidence ratios was 0.7 (95% confidence interval [CI], 0.5-0.9) in Mecklenburg County. In Alabama, 6 individuals who were identified as either attending Auburn University or employed there from 1989 to 1993 had diagnoses of UM. Initial SIR calculations for white females of all ages was 1.15 (95% CI, 0.989-1.328). In New York, SIR for Broome and Tioga counties were 0.93 and not significant. However, in Tioga county, for males and females and females alone, SIRs were 2.00 (P = .04) and 3.33 (P = .006).

CONCLUSIONS

Although most of the conclusions that the SIR does not meet statistical criteria that defines these accumulations as true "cancer clusters," considering the incidence and demographics of UM, these accumulations of cases is unexpected and worth additional exploration. Further investigation into these cases with additional geospatial analyses and blood and tumor testing is ongoing. Information learned from the study of these unique populations may inform a better understanding of the pathogenesis of UM.