"Location of cutaneous malignant melanoma in Sweden 2004-2018 - mortality and sex differences"

Cutaneous malignant melanoma (CMM) is one of the most common causes of cancer-related death in Sweden. There is increasing evidence that localisation of the primary CMM lesion differs between sexes and is associated with different outcomes. However, definitive convincing data is lacking.

To describe changes in the distribution of CMM anatomical location over time according to sex and determine differences in mortality by location.

This is a retrospective nation-wide cohort study of all patients diagnosed with CMM in Sweden between 2004 and 2018. Hazard ratios (HRs) were calculated using a multivariate cox regression model adjusting for age, sex, T-stage, multiple melanomas and comorbidities.

A total of 68,666 patients were included. In males, trunk CMM was the most common location (51% of all male CMM), with an increasing proportion over time. In females, lower extremity CMM had the largest proportion in 2004 (33%) followed by trunk CMM (27%). By 2018, trunk CMM became more common than lower extremity CMM in females. Upper and lower extremity CMMs had lower HR for all-cause mortality compared with trunk CMM (0.896 and 0.887, respectively, p<0.001), while head and neck CMM had higher HR compared with trunk CMM (1.090, p<0.001). Males had greater risk than females (HR 1.352, p<0.001).

Head and neck CMMs were associated with increased risk of all-cause mortality, while both upper and lower extremity CMMs were associated with decreased risk. Both sexes had increasing proportions of trunk and upper extremity CMM over time, with corresponding decreases in lower extremity and, head and neck CMM.