Globally,
thyroid cancer accounts for 2 % of all
cancer diagnoses, and can be classified as well-differentiated or undifferentiated. Currently, differentiated
thyroid carcinomas have good prognoses, and can be treated with a combination of
therapies, including surgical
thyroidectomy, radioactive
iodine therapy and
hormone-based
therapy. On the other hand,
anaplastic thyroid carcinoma, a subtype of undifferentiated
thyroid carcinoma characterized by the loss of thyroid-like phenotype and function, does not respond to either radioactive
iodine or
hormone therapies. In most cases,
anaplastic thyroid carcinomas are diagnosed in later stages of the disease, deeming them inoperable, and showing poor response rates to systemic
chemotherapy. Recently, treatment courses using multiple-target agents are being explored and clinical trials have shown very promising results, such as overall survival rates, progression-free survival and
tumor shrinkage. This review is focused on
thyroid carcinomas, with particular focus on
anaplastic thyroid carcinoma, exploring its undifferentiated nature. Special interest will be given to the treatment approaches currently available and respective obstacles or drawbacks. Our purpose is to contribute to understand why this
malignancy presents low responsiveness to current treatments, while overviewing novel
therapies and clinical trials.