Nevertheless, this sex difference is far less pronounced before puberty and after menopause. Several epidemiological studies have examined several reproductive traits, but the cause of this increased prevalence of thyroid cancer in women is unclear. The annual incidence of thyroid cancer varies considerably in different registries, with the highest incidence rates in the world reported in Hawaii and Iceland (Ferlay et al., 2007; Kolonel et al., 1990). In Europe, the highest incidence occurs in Iceland, followed by Finland, while relatively low incidence characterizes the United Kingdom and Denmark (Ferlay et al., 2007,). These differences have been attributed to ethnic or.
