Space-time clustering and seasonality in diagnosing skin cancers in Wallonia (south-east Belgium).

Background: In Westernized populations, the number of diagnosed cases of primary cutaneous cancers, particularly malignant melanomas and basal cell carcinomas (BCC), has been previously shown to fluctuate during specific periods of the year.

Objective And Method: The aim of the present 6-year study was to explore the seasonality if any in skin cancer detection in Wallonia (south-east Belgium).

Results: For both malignant melanomas and BCC late spring/early summer and mid-autumn were the periods of highest diagnosis prevalence irrespective of gender. The amplitude of this bimodal evolution remained within the range of 2 standard deviations around the monthly means. Similar seasonal variations were also found in non-neoplastic controls consisting of laboratory samplings of onychomycoses and non-infectious onychodystrophies.

Conclusion: There is reason to believe that this timing and rhythm is unrelated to any specific cancer chronomics. Rather, the present findings suggest unspecific seasonality in diagnosing skin disorders including malignancies. A variable patient awareness of changing aspects of the skin according to seasons probably represents the major influence of the described space-time clustering of skin cancer diagnosis.