The environmental pollution role in increasing the incidence of thyroid cancer in Tuscany (Italy)

BACKGROUND: The incidence of thyroid cancer (TC) in Italy is one of the highest in Europe; the reason for this is unclear. Some studies investigated the potential role of toxic elements related to geological and/or anthropogenic sources in increasing the incidence of TC. The aim of our study is to further investigate the connection between higher TC incidence and environmental pollution; that is fundamental to implement prevention practices and to increase awareness of environmental issues. METHODS: The Tuscany Cancer Registry provided us the number of cases of TC patients for all the provinces of Tuscany during the period from 2013 to 2017. Provinces were grouped in exposed/unexposed to several environmental pollutants. In particular, they were stratified based on the presence of mines, on the presence of geothermal plants and on the ministerial classification in “contaminated sites” and no “contaminated sites”, i.e. areas in which an alteration of the characteristics of the environmental soil matrix, subsoil and groundwater has been ascertained such as to represent a risk to human health. Rate ratios (RR) and their 95% confidence interval (CI) were estimated. RESULTS: Contaminated sites have significantly higher incidence then uncontaminated ones (male RR: 1.2, CI: 1.05-1.364, p = 0.008; female RR of 1.12, CI: 1.03-1.21, p = 0.009). Similar results were obtained stratifying for the presence of mines (male RR: 1.25 CI: 1.12-1.40, p < 0.001; female RR: 1.35, CI: 1.26-1.45, p < 0.001) and then of geothermal plants (male RR: 1.22 CI: 1.06-1.40, p < 0.001; female RR: 1.40, CI: 1.29-1.52, p < 0.001). CONCLUSIONS: Further laboratory experiments are needed to confirm the connection between specific pollutants and TC. If these findings will be confirmed a stringent legislation and environmental polices have to be taken to reduce the TC incidence. In this way, also the cost of healthcare management of patients with TC can be reduced. KEY MESSAGES: • Pollutants could affect both the environment and people health. • The prolonged exposure to pollutions could increase thyroid cancer incidence.