Seasonal variations in the diagnosis of cutaneous melanoma.

Seasonal patterns in diagnosis were examined in 7836 patients with cutaneous melanoma (clinical stage I and II) documented at the Department of Dermatology and Allergology at Ludwig-Maximilian-University in Munich, Germany, between 1977 and 2000. Of these patients, 2362 were first given a diagnosis in the summer months (June-August) and 1757 were first given a diagnosis in the winter months (December-February). A summer-to-winter ratio was determined for sex, age, anatomic tumor site, histopathologic subtype, and tumor thickness. The summer-to-winter ratio was 1.34 (95% confidence interval: 1.27-1.43) for all patients, with a ratio of 1.22 (95% confidence interval: 1.12-1.33) for men and 1.47 (95% confidence interval: 1.35-1.60) for women. The frequency of diagnosis of cutaneous melanoma was seasonal for all age classes, for all anatomic tumor sites, for all histopathologic subtypes except acrolentiginous melanomas, and for melanomas with a tumor thickness <3.0 mm. Comparing subgroups of the above-mentioned clinical and histopathologic parameters, significant differences could be observed for sex and anatomic tumor site. On the basis of this data, possible explanations for the diagnostic summer peak may be a greater awareness as a result of clothing habits in summertime or because of incurred sunburns in patients with skin type I and II, and the influence of public-health campaigns usually performed at the beginning of summer.