Trends in histological subtypes of cutaneous melanoma in the Netherlands from 1989 to 2023 - Influence of sunlight exposure and overdiagnosis.

Abstract

Introduction: Melanoma incidence has continued to increase over the past decades with unchanged mortality. Different sunshine exposures across the generations complicate the interpretation of the trends. It is further suggested that half of the rising incidence rate is caused by overdiagnosis. We compared the time trends in the major but not all sunlight-related histological subtypes of cutaneous melanoma in the Netherlands in 1989-2023.

Methods: With data from the Netherlands Cancer Registry, trends were assessed for superficial spreading melanoma (SSM, n=93,067), lentigo maligna melanoma (LMM, n=26,237), and nodular melanoma (NM, n=15,658). Numbers and rates were analysed by age, calendar period, and birth cohort for people born in 1925-1985. To study significant changes across the years, the joinpoint regression model was used. For the projection of new cases to 2043, we applied the Nordpred method.

Results: During the past 25 years, age-standardised incidence rates for melanoma in situ increased ninefold, for invasive melanoma threefold. Significant rises were noted for SSM and LMM (fourfold) and NM (twofold). The successively born cohorts showed consistent increases in incidence rate for SSM and LMM, but to a lesser degree for NM. Around 2030, the incidence rates for all types of melanomas are expected to be highest, at approximately 100 per 100,000 population.

Conclusions: The incidence of melanoma showed a steady increase from 1989 onwards. This was before early detection (that may cause overdiagnosis), was put into clinical practice. Birth cohort analysis of trends in histological subtypes will further contribute to the quantification of overdiagnosis.