Seasonal variation in high-risk phenotypes of cutaneous malignant melanoma diagnosed in Eastern England: An observational study

Background: Despite seasonal variation in malignant melanoma diagnosis being well described, data on the annual variation in high-risk melanomas are scarce. Objectives: We set out to investigate the relationship between seasonality, the incidence of melanoma, and the distribution of melanoma characteristics, including Breslow thickness, ulceration, mitotic rate, lymphovascular and perineural invasion, and the presence of microsatellites. Methods: Primary cutaneous malignant melanomas diagnosed between 2011 and 2019 in Eastern England were identified from our prospectively maintained melanoma database (n = 2199). These were analysed by year and season of diagnosis, patient demographics, and melanoma characteristics. Results: There was a variation in rates of melanoma diagnosis across the year, with Summer having the highest incidence (p < 0.0001). There was a significant trend towards more male than female diagnosis in Winter (p = 0.0354). There were no significant seasonal trends in Breslow thickness, ulceration, tumour infiltrating lymphocytes, or mitotic rate. Multivariate analysis showed that microsatellites were more likely to be diagnosed in the Winter (OR=2.00 (1.19-3.43), p = 0.010), lymphovascular invasion significantly more likely to be diagnosed in Autumn (OR=1.78 (1.16-2.76), p = 0.009), and perineural invasion was more likely to be diagnosed in the Summer (OR=0.44 (0.23-0.79), p = 0.007). Conclusions: These data confirm that high-risk phenotypes are associated with increasing Bres-low thickness and mitotic rate. However, season variability as an independent risk factor for the phenotypes is a novel finding. (c) 2022 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the impact of seasonality on malignant melanoma and found that the diagnosis rate of melanoma is highest in summer, and there are more male melanoma diagnoses in winter. Seasonality does not significantly affect melanoma characteristics such as Breslow thickness, ulceration, lymphovascular invasion, and perineural invasion. However, microsatellites are more likely to be diagnosed in winter, lymphovascular invasion is more likely to be diagnosed in autumn, and perineural invasion is more likely to be diagnosed in summer.