Positive effect of fetal cell microchimerism on tumor presentation and outcome in papillary thyroid cancer.

Studies on both circulating and tissue fetal cell microchimerism (FCM) favored its protective role in thyroid cancer, consistent with findings in other malignancies. Nevertheless, scanty data were available on the possible impact on the outcome of the disease. We demonstrated that FCM has a positive effect on thyroid cancer presentation and outcome. We also excluded that the better clinical features observed were due to the effect of pregnancy per se. In conclusion, FCM may have not only a protective role toward the onset of thyroid cancer, but also a positive effect on its progression. These findings give novel insights into the identification of the role of FCM in oncology and, consequently, in the potential therapeutic application of this physiological phenomenon.