New approaches to image thyroid cancer cells and microenvironment.

Poorly differentiated thyroid cancer (PDTC) and undifferentiated thyroid cancer (UDTC) are still life-threatening pathologies, because of the lack of well-established diagnostic and therapeutic approaches. In the past, many attempts have been made to develop radiopharmaceutical to diagnose or treat radioactive iodine (RAI)-refractory metastases or recurrences, with limited results. Indeed, it was not possible to find a specific and overexpressed marker to be used as target of radiopharmaceuticals or targeted therapies. Nowadays, with novel advances in the field of tumor microenvironment, many new markers are available to be used as suitable targets for targeted therapies interfering with signalling pathways of cells involved in the mechanisms that favour tumor growth and metastatization. This opened new perspective in the use of radiopharmaceuticals targeting components of tumor microenvironment for early diagnosis, pre-operative staging or therapy planning and follow up with targeted drugs. In the present review we present the state of novel approaches to image thyroid cancer and its microenvironment, focusing on RAI-refractory thyroid cancer as a real clinical problem to be solved.