A Reports and Review on Colorectal Cancer Metastases to the Thyroid Gland

Background: Secondary malignancies of the thyroid gland are a rare finding in clinical practice. In adittion, colorectal metastasis to the thyroid (CMT) are even more unfrequently diagnosed. The source of the primary tumour follows demographic and ethnical patterns, reflecting the most prevalent malignancies in the different populations. Colorectal cancer is one of the most common types of cancer worlwide, but in spite of it, CMT are infrequently diagnosed. Most of them are identifyed during the follow up of gastrointestinal primary malignancies. Due to the improvement of image techniques, oncological treatment and follow up, survival and consequently diagnosis of metastatic disease is more frequent. Those facts make this entity a dignostic and therapeutical challenge, due to the lack of information and the difficulties to perform clinical trials and research.

Case Summary: Case report of a patient diagnosed of a CMT of adenocarcinoma of the rectum evidenced during follow up, four years after neoadyuvant chemo- radiotheraphy, subsequent curative surgical treatment of the primary tumour, and intercurrent lung bilateral metastases.

Conclusions: Thyroid metastases of extrathyroid origin is an uncommon finding, even rarer if accounting for CMT. The diagnostic process, as well as survival of oncologic patients is improving, and consequently the number metastases to the thyroid gland is increasing.

In spite of it, management and outcome of the pacients affected remains unclear, beeing necessary more clinical research to define diagnostic and therapeutic protocols, in order to provide our patients of a suitable treatment and a possitive impact on their outcome.