Incidence and survival of cutaneous melanoma in Belgium and The Netherlands from 2004-2016: striking differences and similarities of two neighboring countries.

BACKGROUND: Cutaneous melanoma (CM) is a multifactorial disease, with both environmental and genetic factors involved. The incidence of CM has risen rapidly during the last decades, making it a growing public health problem.

OBJECTIVES: The purpose of this retrospective study was to compare incidence and survival data of CM between two neighboring countries, Belgium (BE) and The Netherlands (NL).

METHODS: Data were collected by the Belgian Cancer Registry (BCR) and the Netherlands Cancer Registry (NCR) from 1 January 2004 until 31 December 2016. Mucosal melanoma, in situ CM and melanoma in children from 0 to 14 years were excluded. Age-standardized incidence rates were calculated using the World Standard Population (WSR) per 100.000 persons. Five-year relative survival ratios were calculated using the Ederer II methodology.

RESULTS: Total number of CM was higher in NL (63.789) compared to BE (27.679). The WSR was 1.5 times higher in NL compared to BE (27.7 vs 18.6/100.000/year). The WSR of stage IV tumors was higher in BE than in NL (0.3 vs 0.2/100.000/year). Five-year relative survival of stage IV tumors was higher in BE compared to NL (27.2% vs 13.7%).

CONCLUSIONS: Incidence of CM was higher in NL, indicating a higher risk of CM diagnosis. Stage IV tumors were relatively more frequent in BE for both sexes, while relative survival of stage IV tumors was higher in BE. As geographical location and latitude of both neighboring countries are almost identical, other factors like differences in behavior, follow-up and/or treatment may explain these differences.