The 'rings of fire' and thyroid cancer.

Several studies have revealed an increased incidence of thyroid cancer in volcanic areas around the world. Hawaii and the Philippines on the rim of the Pacific Ocean, where the greatest number of volcanoes are located at convergent plate boundaries, are among the regions with the highest incidence of thyroid carcinoma worldwide. Iceland is another region also rich in volcanoes in which the highest incidence of thyroid cancer in Europe is found. The common denominator of these regions is their numerous volcanoes and the fact that several constituents of volcanic lava have been postulated as being involved in the pathogenesis of thyroid cancer. This article aims at presenting pertinent data that could link a volcanic environment to thyroid cancer.