Latitude gradient for melanoma incidence by anatomic site and gender in Norway 1966-2007.

Latitude gradients and time trends for cutaneous malignant melanoma (CMM) were analyzed using incident cases from the Norwegian Cancer Registry for the period 1966-2007. Sex and various anatomic regions of the body were taken into account, for better understanding of the role of ultraviolet radiation in CMM etiology. There is a latitude gradient for CMM on all body sites included in the present study, with 2-2.5 times higher incidence rates in the south. The latitude gradients seem to be largest for the trunk. Melanomas on sites intermittently exposed to the sun (like the trunk) dominate both in the north and in the south and this distribution has not changed over the years. A leveling off of the incidence rates are observed for both sexes and for all sites studied, after 1985-1995, slightly more in the south than in the north, except for the head and neck where the incidence rates have continued to increase slowly in the north as well as in the south. The leveling off of melanoma trend is probably associated with melanoma prevention campaigns and with increasing awareness, although vitamin D could play a role.